A device for switching between normal and reverse drive force, in which, in output of drive force having a specific rotational direction from the input side to the load side, the drive force is outputted by appropriately switching between the normal and reverse rotation. The device has an input gear (11), an output gear (12), and a switchover mechanism (13). The switchover mechanism (13) is constructed from a planetary gear mechanism (14), a control mechanism (15), and a clutch mechanism (16). The planetary gear mechanism (14) has a sun gear (19) integral with a rotation transmission shaft (18), an internally toothed gear (21) integral with the output gear (12), planetary gears (22) arranged between the sun gear (19) and the internally toothed gear (21), and carrier (23). The control mechanism (15) has a control gear (25) capable of selectively having a restrained state and a non-restrained state by the function of an actuator (24). The clutch mechanism (16) has a one-way roller clutch (26) placed between the rotation transmission shaft (18) and a clutch installation section (34) provided on the carrier (23). When the actuator (24) is off, the roller clutch (26) is locked to allow the planetary gears (22) to perform only revolution, causing an input of a normal rotation direction (A) to be directly outputted. When the actuator is on, the lock of the roller clutch (26) is released to allow the planetary gears (22) to perform only rotation, causing an input of the normal rotation direction (A) to be outputted with the direction of the rotation switched to a reverse rotation direction (B).