To significantly shorten drying necessary time by effectively transferring heat of an inner circumference face 3a to a heating object w in the inner circumference face 3a by a simple structure, and to prevent easy damaging of an arm 15 or a blade body 16 caused by torque transmitted to them.

The vacuum dryer is provided with the inner circumference face 3a to be heated, the arm 15 turned around a center line of the inner circumference face 3a, and the blade body 16 for promoting heating of the heating object fixed to a tip of the arm 15. It is composed such that the blade body 16 is comprised of a flat plate body comprised of an elastic body, the flat plate body 16 is arranged substantially in parallel with the center line, and a front edge b1 and a rear edge b2 are pressed against the inner circumference face 3a in a horizontal linear state or narrow end panel state. The flat plate body 16 is shaped like a parallelogram, and it is detachably fixed to the tip of the arm 15 by screw coupling.