An array antenna includes: a plurality of first antenna elements arrayed at specified element intervals on a plane of a board; a plurality of second antenna elements arrayed at the element intervals in parallel to an array direction of the first antenna elements on the plane; a first power supply circuit for supplying electric power to the respective first antenna elements by a line branched at a first branch point on the plane; and a second power supply circuit for supplying electric power to the respective second antenna elements by a line branched at a second branch point shifted by a specified distance in the array direction with respect to the first branch point on the plane.