A portable wireless sensor includes a power source, a sensor, a wireless communication circuit and a sensor control circuit obtaining data from the sensor and transmitting the data to outside through the wireless communication circuit, in which the power source includes a secondary battery, a power reception circuit receiving electric power supply in a non-contact manner, and a power source control circuit controlling charging of the secondary battery with the electric power received by the power reception circuit. The wireless sensor includes a standard mode to transmit the data obtained from the sensor to outside through the wireless communication circuit, and a diagnosis mode to diagnose at least one of the secondary battery and the sensor portion in a case where the power reception circuit receives electric power supply in a non-contact manner.