According to one embodiment, an electronic apparatus includes a power transmitter, detect circuitry and control circuitry. The power transmitter is configured to transmit a power by an electromagnetic wave of a power transmission frequency band according to a power transmission period. The detect circuitry is configured to detect a power in a frequency band different from the power transmission frequency band. The control circuitry is configured to determine the power transmission period based on a first threshold value, a second threshold value, a third threshold value and a fourth threshold value.