According to one embodiment, a receiver, which is configured to receive a radio signal having a preamble including a synchronization pattern and a payload containing data, includes an antenna, a low noise amplifier, a down-conversion module, a variable gain amplifier, an auto gain controller, a synchronization acquisition module, and a demodulator. The antenna is configured to receive the radio signal. The low noise amplifier is configured to amplify an output from the antenna by applying a first variable gain. The down-conversion module is configured to down-convert an output from the low noise amplifier. The variable gain amplifier is configured to amplify an output from the down-conversion module by applying a second variable gain. The auto gain controller is configured to, in accordance with strength of the radio signal, firstly adjust the first variable gain, and after fixing the first variable gain, adjust the second variable gain.