To provide a drive device which drives a driven body to change its attitude, in particular, a fluid pressure drive device which drives a driven body by introducing a fluid pressure into an actuator.

The fluid pressure drive device includes the actuator 2 which has two pressure chambers 21, 22 and is driven under the fluid pressures introduced into the pressure chambers 21, 22, a passage 10 which is communicated with each of the pressure chambers 21, 22, and a two-way discharge pump P which is provided in a portion of the passage 10 and driven by a motor M. The operation direction of the actuator 2 is changed over by changing over the discharge direction of the two-way discharge pump P. In this device, a self-locking gear 3 is provided between the two-way discharge pump P and the motor M. The self-locking gear 3 reduces the rotational speed of the motor M, transmits the rotation to the two-way discharge pump P, and is not be rotated by a torque input from the two-way discharge pump P side.