To provide a microwave drying device for heating and drying a dried object containing water in a short time by continuously projecting high power microwaves.

A water supply pipe 16 formed of a microwave transmissive material passes through a microwave heating furnace 11 while communicating the inside of the microwave heating furnace 11 with the outside thereof. The microwaves are absorbed by water supplied to the water supply pipe 16, depending on a reduction in the water content of the dried object 10, thus preventing scorching due to overheat and plasma discharge.