Power steering apparatus

A power steering apparatus includes a steering shaft 10 including an input shaft 11, an intermediate shaft 13 connected through a first torsion bar 12 to the input shaft, and an output shaft 15 connected through a second torsion bar 14 to the intermediate shaft; a hollow motor 30 to provide a rotational force to the intermediate shaft; and a control device 60 including a microcomputer, and including an output shaft rotation angle presuming section 63 to presume an output shaft rotation angle θg based on signals of an input shaft rotation angle θh and an intermediate shaft rotation angle θm, a torsion spring constant g1 and g2 of the first and second torsion bars; and a motor drive control section 69 to control the hollow motor based on the output shaft rotation angle.