To provide a caulking gun capable of reducing the length of the caulking gun when it is used, and capable of quick operation even in a small space.

The caulking gun includes a gun body, a caulking cartridge holder and a caulking agent extruding device. A supporting part and a handle part are formed under the gun body in a manner of extending forward and downward. Three guide members are arranged in a space inside the gun body. A guide wheel is pivotally arranged at an upper rear end of the gun body. An extruding member of a long and flexible plate having an arc shape in cross section is arranged in the caulking cartridge holder. An end of the extruding member is connected to an extruding disc in the caulking cartridge holder. The other end of the extruding member penetrates arc-shaped guide holes of upper parts of the three guide members in the gun body and arc-shaped through-holes of upper parts of a propelling member and a position limiting member. The extruding member is then wound around the guide wheel, folded back, extended forward, brought out to the upper side of the caulking cartridge holder from a guide channel, and then is connected to a pulling member.