CONTACTLESS POWER TRANSFER SYSTEM AND POWER TRANSMISSION DEVICE

A contactless power transfer system (1) includes a power supply ECU (250) configured to control an inverter (220) to stop power transmission from a power transmission unit (240) when a current generated in the power transmission unit (240) exceeds a predetermined threshold value due to short-circuiting of a power reception coil comprised in a power reception unit (310). The power supply ECU (250) estimates a coupling state between a power transmission coil comprised in the power transmission unit (240) and the power reception coil, and changes the predetermined threshold value in accordance with the estimated coupling state.