A reflectarray reflects an incident wave in a desired direction, and the reflectarray includes a plurality of elements arranged in a first direction and in a second direction perpendicular to the first direction. The elements reflect the incident wave. A phase of a reflected wave by one element among the plurality of elements differs from a phase of the reflected wave by an element adjacent to the one element in the first direction by a predetermined value, and the phase of the reflected wave by the one element is equal to a phase of the reflected wave by an element adjacent to the one element in the second direction. Gap sizes between patches of a predetermined plural number of elements arranged in the first direction vary from a smallest value to a largest value. Here, an oblique TM incidence is utilized at a spurious resonance frequency.