The present invention is a radio signal transmitting antenna (10) including a first wave source (11) including a plurality of antenna elements (A1 to AN) configured to form a first helical beam (H) for OAM (Orbital Angular Momentum) from the plurality of antenna elements (A1 to AN) and output the first helical beam (H) and a second wave source (15) configured to receive the first helical beam (H) and form a second helical beam (L) output in a constant direction and transmits the second helical beam (L). The radio signal transmitting antenna (10) can transmit a helical beam (L) for OAM with a simplified and smaller device configuration.