Two-dimensional array design techniques are developed for microstrip comb-line antenna array. Low sidelobe design is proposed in the plane parallel to the feeding line. Element radiation is controlled by both widths of the radiating element and the feeding line simultaneously. Beam-tilting design is proposed in the perpendicular plane to the feeding line even though only two feeding lines are arranged. Microstrip slit structure is located around each radiating element in order to cancel reflections from element and slit and to achieve high design accuracy. By using these items, three antennas with different beams are developed for three-beam switching system. Performance of these antennas is evaluated by experiments in the millimeter-wave band.