There is provided a power system including a power transmitting apparatus and a power receiving apparatus. The power transmitting apparatus includes: a power generating unit generating power using renewable energy; a first power measuring unit measuring a power amount generated in a specified period; and a power transmitting unit transmitting the generated power in the specified period and information on the measured power amount to the power receiving apparatus. The power receiving apparatus includes: a power receiving unit receiving the power and the information on the power amount from the power transmitting apparatus; a second power measuring unit measuring a power amount received in the specified period; a determining unit comparing the received power amount and the measured power amount and determining whether such amounts match; and a power reception control unit operable when the amounts do not match, to stop reception of the power and the information.