A rotor (2) of a rotation angle sensor is configured by forming a band-shaped main body (31) of a magnetic steel sheet into a cylindrical shape so that a thickness direction of the band-shaped main body (31) is set as a radial direction. First undulations (32) are provided at a substantially constant pitch on one arc-shaped edge portion of the band-shaped main body (31), and second undulations (33) are provided at a substantially constant pitch on the other arc-shaped edge portion. A first stator (3) is disposed to face the first undulations (32) of the band-shaped main body (31) of the rotor (2), and a second stator (4) is disposed to face the second undulations (33).