To calibrate a chassis dynamometer more precisely.

The roller-side edge of a metal belt 21 is inserted between the circumferential surface of a roller 2 and a stopper bar 242 of a fixture 24 fixed to the roller 2, and a wedge section 211 being firmly fixed to the roller-side edge of the metal belt 21 is fitted between the circumferential surface of the roller 2 and the stopper bar 242, whereby the roller-side edge of the metal belt 21 is fixed to the circumferential surface of the roller 2. Furthermore, the metal belt 21 is brought to pass through an aperture in the upper surface of a pit from its fixed point of the circumferential surface of the roller 2 and to extend above the pit, and is hung about a pulley 221 of a pulley apparatus 22. Then, a prescribed number of weights 23 is suspended by a hook receiver 212 fixed to the edge opposite to the roller-side edge of the metal belt 21.