To provide a bearing device for a camshaft having a simple structure which is excellent in assemblability.

The camshaft 11 for which a plurality of cam pieces 14 are axially provided is rotatably supported between an arc recessed part 41 of a housing member 40 and an arc recessed part 51 of a cap member 50 via roller bearing 20. In an outer circumferential surface of the camshaft 11, annular first and second regulating rings 30, 35 formed separately from the camshaft 11 are positioned at both side parts of an axial direction of the roller bearing 20 and respectively press-fitted and fixed. Regarding surfaces confronting the first and the second regulating rings 30, 35 as sliding surfaces 31, 36, these sliding surfaces 31, 36 receive axial load by contacting with both side surfaces of at least one of the housing member 40 and the cap member 50.