According to one embodiment, a radar apparatus includes a signal processing device that has a first circuit, a second circuit and a transmitter. The first circuit is configured to determine whether or not there is a radio interference based on a radio signal received via an antenna. The second circuit is configured to, when the first circuit determines that there is the radio interference, select a predetermined pulse pattern based on an avoiding function of a wireless communication device having the avoiding function of the radio interference, the predetermined pulse pattern being separately defined from a pulse pattern of transmission processing for operating a radar. The transmitter is configured to transmit from the antenna a radio signal matching the pulse pattern selected by the second circuit.