The radar module comprises a vertical layered block of a planar array antenna, a signal delay section, and a transmitter-receiver section. The planar array antenna comprises: four antenna portions different in beam direction; and a selective connection section for selectively connecting each antenna portion with the signal delay section. Reducing the number of parts, saving the production cost and miniaturizing the apparatus is achieved by an arrangement in which a single transmitter-receiver section is in common use with a plurality of antenna portions. The signal delay section comprises a spiral dielectric line with a metal layer covering around a dielectric of rectangular section to achieve ensuring the delay time and reducing the package area.