Drive unit for electric bicycle

A drive unit for an electric bicycle, the drive unit including a motor (500)configured to generate a rotary force to drive a wheel (50) of the electric bicycle, a reduction gear unit provided with a plurality of gears (511, 512, 514, 521, 522) to decelerate a rotary force generated from the motor, and a ring gear (524) configured to output the rotary force which is decelerated by the reduction gear, wherein a rib (524a) is formed on at least one of two lateral sides of the ring gear (524).