A power supply device supplies electric power to a power receiving device including a power receiving unit in a non-contact manner. The power supply device includes a power source device that generates electric power with a predetermined frequency; a power transmitting unit that receives the electric power from the power source device, and that resonates with the power receiving unit through an electromagnetic field, thereby transmitting the electric power to the power receiving unit in the non-contact manner; a detection device that detects reflected electric power to the power source device; a communication device that receives information regarding a power receiving situation in the power receiving device; and a control device that controls electric power transmission from the power transmitting unit based on the information regarding the power receiving situation and the reflected electric power.