A plastic drying apparatus that uses microwave heating as means of heating a plastic thereby allowing the surface as well as the inside of particles of the plastic to be heated simultaneously and therefore can attain to bring the plastic to a highly dried state within a short period of time. A certain amount of a plastic is fed into a plastic drying tank. While the plastic is stirred, the plastic is heated and dried uniformly by microwaves generated by a microwave generating unit. The humidity is measured by a humidity measuring sensor and the plastic is highly dried automatically. Dried air nozzles are provided to the wall surface of the plastic drying tank for discharging air in a super-dried state in a widely flared manner so as to prevent the plastic powder, etc. from adhering.