According to one embodiment, a radar apparatus includes first antennas, a second antenna, and a third antenna. If the first antennas are used as transmission antennas, the second and third antennas are used as reception antennas. If the second and third antennas are used as the transmission antennas, the first antennas are used as the reception antennas. The first antennas are arranged in a first direction at a first distance and in a second direction crossing the first direction at a second distance. A distance between the second antenna and the third antenna in the first direction is approximately equal to a product of the first distance and a number of first antennas arranged in the first direction.