The present invention relates to a personal, green-energy, transportation device with single wheel and self-balancing function. The personal, green-energy, transportation device can be propelled by the manpower and simultaneously execute the self-balancing function thereof. The device comprises: a body, a wheel, a pedal portion, a roller chain, an in-wheel motor, and a sensing-control module, wherein the sensing-control module detects the balancing condition of the body when the personal, green-energy, transportation device is driven, and then the sensing-control module controls the in-wheel motor to output a balancing torque for maintaining the self balance of the body.