To provide a resin pellet drying device which keeps the inside of a heating-drying means under a specified pressure-reduced state by surely closing the opening section by a simple structure, and reduces costs of the device itself by the simple structure.

A flexible opening/closing plate, and an opening/closing means having an opening/closing operation member are respectively provided. In this case, the flexible opening/closing plate has an opening section having approximately the same size as a transferring passage and a shielding section which shields the passage on the upstream side in the transferring direction of resin pellets in a feeding hopper and a discharging hopper, and is movably supported in the horizontal direction under an approximately air-tight state. The opening/closing operation member selectively locates the opening section and the shielding section on the transferring passage by moving the opening/closing plate in the horizontal direction.