An endoscope includes an insertion portion having a bending portion, a base portion connected to the insertion portion, an operation wire extending from the bending portion toward the base portion, a drive source unit which is provided in the base portion, and a drive force transmission unit which is connected to the operation wire and the drive source unit. The drive source unit includes a first frame, a second frame, a motor, a gear box and a potentiometer. The gear box includes a horizontal power transmission mechanism for horizontally transmitting power from the motor, and an epicyclic gear mechanism for vertically transmitting power from the horizontal power transmission mechanism.
