Power transmitting device and power receiving device

A power receiving device that receives electric power in a non-contact manner from a power transmitting device provided outside, comprising:

• a power receiving coil that receives electric power in a non-contact manner from a power transmitting coil of said power transmitting device through a magnetic field, said magnetic field being formed by said power transmitting coil when an AC voltage is applied thereto;
• a foreign object detector that detects a foreign object located below or in the vicinity of said power receiving device;
• a magnetic field detector that detects said magnetic field;
• and
• a control device that receives information about a result of the detection of a foreign object by said foreign object detector and information about a result of the detection of said magnetic field by said magnetic field detector,
• said control device determining whether there is a foreign object or not based on the result of the detection of a foreign object performed by said foreign object detector during a timing period when the strength of said magnetic field that is detected by the magnetic field detector while electric power transmission is being performed is equal to or lower than a prescribed value.