diff --git a/coretk/coretk/dialogs/marker.py b/coretk/coretk/dialogs/marker.py
new file mode 100644
index 00000000..8a476548
--- /dev/null
+++ b/coretk/coretk/dialogs/marker.py
@@ -0,0 +1,53 @@
+"""
+marker dialog
+"""
+
+from tkinter import ttk
+
+from coretk.dialogs.colorpicker import ColorPicker
+from coretk.dialogs.dialog import Dialog
+
+MARKER_THICKNESS = [3, 5, 8, 10]
+
+
+class Marker(Dialog):
+    def __init__(self, master, app, initcolor="#000000"):
+        super().__init__(master, app, "marker tool", modal=False)
+        self.app = app
+        self.color = initcolor
+        self.radius = MARKER_THICKNESS[0]
+        self.draw()
+
+    def draw(self):
+        button = ttk.Button(self.top, text="clear", command=self.clear_marker)
+        button.grid(row=0, column=0)
+
+        frame = ttk.Frame(self.top)
+        frame.grid(row=1, column=0)
+
+        button = ttk.Button(frame, text="radius 1")
+        button.grid(row=0, column=0)
+        button = ttk.Button(frame, text="radius 2")
+        button.grid(row=0, column=1)
+        button = ttk.Button(frame, text="radius 3")
+        button.grid(row=1, column=0)
+        button = ttk.Button(frame, text="radius 4")
+        button.grid(row=1, column=1)
+
+        label = ttk.Label(self.top, background=self.color)
+        label.grid(row=2, column=0, sticky="nsew")
+        label.bind("<Button-1>", self.change_color)
+
+        # button = ttk.Button(self.top, text="color", command=self.change_color)
+        # button.grid(row=2, column=0)
+
+    def clear_marker(self):
+        canvas = self.app.canvas
+        for i in canvas.find_withtag("marker"):
+            canvas.delete(i)
+
+    def change_color(self, event):
+        color_picker = ColorPicker(self, self.app, self.color)
+        color = color_picker.askcolor()
+        event.widget.configure(background=color)
+        self.color = color
diff --git a/coretk/coretk/graph/graph.py b/coretk/coretk/graph/graph.py
index 77cc2264..e0878f20 100644
--- a/coretk/coretk/graph/graph.py
+++ b/coretk/coretk/graph/graph.py
@@ -12,7 +12,7 @@ from coretk.graph.enums import GraphMode, ScaleOption
 from coretk.graph.linkinfo import LinkInfo, Throughput
 from coretk.graph.node import CanvasNode
 from coretk.graph.shape import Shape
-from coretk.graph.shapeutils import ShapeType, is_draw_shape
+from coretk.graph.shapeutils import ShapeType, is_draw_shape, is_marker
 from coretk.images import Images
 from coretk.nodeutils import NodeUtils
 
@@ -45,6 +45,7 @@ class CanvasGraph(tk.Canvas):
         self.ratio = 1.0
         self.offset = (0, 0)
         self.cursor = (0, 0)
+        self.marker_tool = None
 
         # background related
         self.wallpaper_id = None
@@ -499,10 +500,22 @@ class CanvasGraph(tk.Canvas):
             self.drawing_edge = CanvasEdge(x, y, x, y, selected, self)
 
         if self.mode == GraphMode.ANNOTATION and selected is None:
-            shape = Shape(self.app, self, self.annotation_type, x, y)
-            self.selected = shape.id
-            self.shape_drawing = True
-            self.shapes[shape.id] = shape
+            if is_marker(self.annotation_type):
+                r = self.app.toolbar.marker_tool.radius
+                self.create_oval(
+                    x - r,
+                    y - r,
+                    x + r,
+                    y + r,
+                    fill=self.app.toolbar.marker_tool.color,
+                    outline="",
+                    tags="marker",
+                )
+            else:
+                shape = Shape(self.app, self, self.annotation_type, x, y)
+                self.selected = shape.id
+                self.shape_drawing = True
+                self.shapes[shape.id] = shape
 
         if selected is not None:
             if selected not in self.selection:
@@ -573,6 +586,18 @@ class CanvasGraph(tk.Canvas):
             if is_draw_shape(self.annotation_type) and self.shape_drawing:
                 shape = self.shapes[self.selected]
                 shape.shape_motion(x, y)
+            elif is_marker(self.annotation_type):
+                marker_tool = self.app.toolbar.marker_tool
+                r = marker_tool.radius
+                self.create_oval(
+                    x - r,
+                    y - r,
+                    x + r,
+                    y + r,
+                    fill=self.app.toolbar.marker_tool.color,
+                    outline="",
+                    tags="marker",
+                )
 
         if self.mode == GraphMode.EDGE:
             return
diff --git a/coretk/coretk/graph/shapeutils.py b/coretk/coretk/graph/shapeutils.py
index a566a713..0e2cc29c 100644
--- a/coretk/coretk/graph/shapeutils.py
+++ b/coretk/coretk/graph/shapeutils.py
@@ -17,3 +17,7 @@ def is_draw_shape(shape_type):
 
 def is_shape_text(shape_type):
     return shape_type == ShapeType.TEXT
+
+
+def is_marker(shape_type):
+    return shape_type == ShapeType.MARKER
diff --git a/coretk/coretk/toolbar.py b/coretk/coretk/toolbar.py
index 323c5d67..96b317c2 100644
--- a/coretk/coretk/toolbar.py
+++ b/coretk/coretk/toolbar.py
@@ -6,9 +6,10 @@ from tkinter import ttk
 from tkinter.font import Font
 
 from coretk.dialogs.customnodes import CustomNodesDialog
+from coretk.dialogs.marker import Marker
 from coretk.graph import tags
 from coretk.graph.enums import GraphMode
-from coretk.graph.shapeutils import ShapeType
+from coretk.graph.shapeutils import ShapeType, is_marker
 from coretk.images import ImageEnum, Images
 from coretk.nodeutils import NodeUtils
 from coretk.themes import Styles
@@ -57,6 +58,9 @@ class Toolbar(ttk.Frame):
         self.network_picker = None
         self.annotation_picker = None
 
+        # dialog
+        self.marker_tool = None
+
         # draw components
         self.draw()
 
@@ -401,6 +405,9 @@ class Toolbar(ttk.Frame):
         self.annotation_button.image = image
         self.app.canvas.mode = GraphMode.ANNOTATION
         self.app.canvas.annotation_type = shape_type
+        if is_marker(shape_type):
+            self.marker_tool = Marker(self.master, self.app)
+            self.marker_tool.show()
 
     def click_run_button(self):
         logging.debug("Click on RUN button")
@@ -410,6 +417,8 @@ class Toolbar(ttk.Frame):
 
     def click_marker_button(self):
         logging.debug("Click on marker button")
+        dialog = Marker(self.master, self.app)
+        dialog.show()
 
     def click_two_node_button(self):
         logging.debug("Click TWONODE button")