A wireless tag processor includes a radio wave transmitting unit that has plural rows of transmitting part groups each having plural transmitting parts that transmit radio waves, the transmitting parts being aligned along a first direction, and the groups being provided in a second direction crossing the first direction, and that transmits radio waves to a wireless tag provided on a medium, and a control section that makes radio waves be transmitted from plural transmitting parts that is arranged staggered, among two rows of the transmitting parts included in the transmitting part groups that are adjacent to each other in the second direction crossing the first direction, and then, makes radio waves be transmitted from other transmitting parts included in the two rows of transmitting parts.