A power steering device for a vehicle includes an input shaft (1) linked to a steering wheel, an output shaft (2) linked to a vehicle wheel, a torsion bar (3) that connects the input shaft (1) to the output shaft (2), and a cylindrical member (13) supported by a housing (12) that is fastened to a vehicle body. The input shaft (1) includes a first input shaft (4) that is inserted into the cylindrical member (13), supported rotatably by the cylindrical member (13), and linked to the steering wheel, and a second input shaft (5) that connects the first input shaft (4) to the torsion bar (3). A connection portion between the first input shaft (4) and the second input shaft (5) is constituted such that a rotation of the first input shaft (4) is transmitted to the second input shaft (5) and the first input shaft (4) is free to move in an axial direction relative to the second input shaft (5).