A drive unit for a bicycle comprising: a rear-wheel hub provided to a rear wheel; a first power system which includes an electric motor including a stator and a rotor, and housed in the rear-wheel hub, and is configured to transmit power of the electric motor to the rear-wheel hub; a rear arm arranged in a first direction as one of a right side and a left side with respect to the rear wheel; a second power system which includes a crank shaft with pedals, a transmission shaft arranged along a rotational center line of the rear-wheel hub, and a power transmission mechanism engaged with the crank shaft and the transmission shaft to transmit the power from the crank shaft to the transmission shaft, and is configured to transmit the power to the rear-wheel hub through the transmission shaft; and an electric wire structure extending from the electric motor and extending along the rear arm, wherein a support is provided to the rear-wheel hub, the support supporting the rear-wheel hub so as to allow the rear-wheel hub to rotate, the rear arm has a first case housing an engaging part between the power transmission mechanism and the transmission shaft, the first case is attached to the support with at least one fixation tool, the electric wire structure extends toward an inside of the rear-wheel hub passing through an electric wire path formed in the support, characterized in that the electric wire structure includes a first electric wire part extending from the electric motor, a second electric wire part extending along the rear arm, and an electric wire coupling part (35,33c,34c) electrically coupling the first electric wire part and the second electric wire part to each other, wherein the electric wire structure extends from the first case toward the inside of the rear-wheel hub passing through the electric wire path formed in the support, and the electric wire coupling part (35,33c,34c) is located between an end surface of the first case in the first direction and an end surface of the rear-wheel hub in a second direction, where the second direction is an opposite direction to the first direction. a rear-wheel hub provided to a rear wheel; a first power system which includes an electric motor including a stator and a rotor, and housed in the rear-wheel hub, and is configured to transmit power of the electric motor to the rear-wheel hub; a rear arm arranged in a first direction as one of a right side and a left side with respect to the rear wheel; a second power system which includes a crank shaft with pedals, a transmission shaft arranged along a rotational center line of the rear-wheel hub, and a power transmission mechanism engaged with the crank shaft and the transmission shaft to transmit the power from the crank shaft to the transmission shaft, and is configured to transmit the power to the rear-wheel hub through the transmission shaft; and an electric wire structure extending from the electric motor and extending along the rear arm, wherein a support is provided to the rear-wheel hub, the support supporting the rear-wheel hub so as to allow the rear-wheel hub to rotate, the rear arm has a first case housing an engaging part between the power transmission mechanism and the transmission shaft, the first case is attached to the support with at least one fixation tool, the electric wire structure extends toward an inside of the rear-wheel hub passing through an electric wire path formed in the support, characterized in that the electric wire structure includes a first electric wire part extending from the electric motor, a second electric wire part extending along the rear arm, and an electric wire coupling part (35,33c,34c) electrically coupling the first electric wire part and the second electric wire part to each other, wherein the electric wire structure extends from the first case toward the inside of the rear-wheel hub passing through the electric wire path formed in the support, and the electric wire coupling part (35,33c,34c) is located between an end surface of the first case in the first direction and an end surface of the rear-wheel hub in a second direction, where the second direction is an opposite direction to the first direction.