PURPOSE: To constitute the titled cordless motor-operated calking gun with an extremely simplified system, by rotating a motor, transmitting the rotating motion with the combination of various gears, and moving a rack to extrude a calking agent.

CONSTITUTION: By rotating a motor 3, said motor 3 is brought into contact with a transmission gear 5 under proper friction force. By the rotating power of a gear supporting plate 7 for holding a free gear 6, the free gear 6 engages the transmission gear 5 with a rack-moving gear 2, rotates the rack-moving gear 2 and moves a rack 1 to extrude a calking agent. By the same way, the motor is reversely rotated to retreat the rack 1. Thus, the cordless motor-operated calking gun which can be used at an optional site is obtained.