An electric ratchet wrench includes a driving member rotatably mounted in a body for driving a fastener. A pawl device is pivotably mounted to the driving member. First and second ring gears are rotatably mounted around the driving member and mesh with the pawl device. A direction switching rod is pivotably mounted to the driving member. A spur gear is mounted on a transmission shaft rotatably received in the body and meshes with the first and second ring gears. A clutch member is mounted on the transmission shaft and is releasably coupled with another clutch member coupled to a motor. The transmission shaft can be driven by the motor to drive the spur gear, the first and second ring gears, and the driving member.