According to one embodiment, a data transmitter includes a radio receiver, a power distributor, a storage module, a radio transmitter, and a power supply. The radio receiver receives a radio signal from an external device. The power distributor distributes power from the radio signal received by the radio receiver. The storage module stores information and is supplied with the power distributed by the power distributor to be readable when no power is supplied from a main power supply. The main power supply supplies power to the entire data transmitter. The radio transmitter is supplied with the power distributed by the power distributor and transmits the information read from the storage module as a radio signal to the external device. The power supply is capable of switching power to be supplied between the power distributed by the power distributor and the power supplied from the main power supply.