A sealant gun includes a main body connected to a C-shaped frame, and a pushing rod extends through the main body and a first end of the C-shaped frame. A connection member located between the first end and the second end of the C-shaped frame is connected with a spherical member which is fixed to the distal end of the pushing rod. A pushing plate has a mounting member and a spherical member is rotatably received in the mounting member so that the pushing plate is rotatable relative to the pushing rod and automatically pushes the sealant tube.