The present invention provides a microwave heating unit formed by comprising: a furnace body in which a fiber inlet and a fiber outlet are formed in a tube wall of a waveguide; and a microwave oscillator which guides microwaves into the waveguide. The microwave heating unit is characterized in that: continuous fibers to be heated are configured to have an inclination of an angle ?? with respect to the tube shaft of the waveguide and to travel therein; the angle ?? is 0.