To provide a wheel nut cap and a wheel nut cap set capable of being detached and reattached from/to a wheel nut without being affected by heat or the state of the wheel nut.

The wheel nut cap 200 capable being detachably fitted to the wheel nut 900 for a vehicle has a bottom 310 provided to cover a cylindrical side wall 320 and one opening of the side wall 320, a wheel nut cap body 300 forming a bottomed cylindrical shape and a magnet 400 attached to the bottom 310, and is constituted so that the wheel nut cap body 300 is fitted to the wheel nut 900 by magnetically attracting the magnet 400 to the wheel nut 900.