To reduce the size, weight and cost of an apparatus itself by reducing the travel resistance of a conveyor chain (17) made of synthetic resin to a support frame (3) to use an electric motor (7) of low torque, and to reduce the size and weight of the conveyor chain (17) made of synthetic resin by reducing the travel resistance of the conveyor chain (17) made of synthetic resin to the support frame (3) to simplify the mutual connection structure of unit members (19) made of synthetic resin.

The conveyor chain (17) made of synthetic resin is constituted by connecting a large number of unit members (19) made of synthetic resin to one another bendably and endlessly by providing a rolling rotation body (31) between each bearing part and each journal part, and making rotatable the rolling rotation body (31) abutting on a chain travel support surface (3a) when the conveyor chain (17) made of synthetic resin and supported to the chain travel support surface (3a) travels for conveyance.