To provide a rotation speed detection device and a rolling bearing device for a wheel using the same improved for inhibiting the positional variations in the radial direction by press-fitting the magnetized member.

A connection part 70 is smoothly bent, and the cross-sectional surface including a central axial line of core metal 66 for fixing the magnetized member is substantially U-shaped. When a cylindrical part 69 of small diameter is force fitted to the slinger, deforms in the radial direction to the out side. Because the connection part 70 is bent smoothly, having large elasticity in the radial direction, it makes the bending rate increase by receiving the deformation of the small cylindrical diameter part 69 and absorbs positional change in the radial direction, to the outside. Accordingly, although the magnetized member fixing core metal 66 as a whole is the width of the radial direction becomes small (thin), a cylinder part of large diameter receiving the deformation of the cylindrical part 68 of large diameter, in the radial direction to the out side, is inhibited by the deformation of the connection part 70.