A wireless power transfer system includes a power transmitter including a high frequency power converter circuit that converts a direct current power into a high frequency power using a switching circuit, a power transmitter coil, and an electric field shield member close to the power transmitter coil and having a structure that uses a conductive member to form an equivalent capacitance between the electric field shield member and the power transmitter coil by electric coupling therebetween during a power transmitting operation such that the value of the equivalent capacitance becomes greater than the value of an equivalent capacitance formed between the power transmitter coil and ground. The power transmitter causes electric potentials in the electric field shield member to be identical using the conductive member, suppresses changes in an electric field in a vicinity of the power transmitter coil, and suppresses radiation of the electric field noise.