To provide a belt drive part capable of preventing the deterioration of accuracy caused by the expansion of a belt without requiring the adjustment of a belt tensioner during assembling in a belt drive part of a camera platform camera.

The belt drive part comprises a driving pulley, a driven pulley, a belt transmitting a rotary force of the drive pulley to the driven pulley, and a flat plate fitting including prescribed deflection and attaching the drive pulley in a direction drawing the belt according to the deflection direction.