Disclosed herein is a wireless power transmitting device that includes: a boost converter boosting an input DC voltage; an inverter converting an output voltage of the boost converter into an AC voltage; a power transmitting coil supplied with the AC voltage to generate an AC magnetic field; a receiving circuit receiving a power transmission command signal; a boost control circuit controlling a boost level of the boost converter according to the power transmission command signal; an operation detection circuit detecting whether or not the boost converter is operated; and an inverter control circuit controlling the inverter. The operation detection circuit activates a stop signal when detecting that the boost converter does not perform operation after an elapse of a predetermined time period from a start of power transmission. The inverter control circuit stops an operation of the inverter in response to the stop signal.