A waveguide circulator which does not cause an arcing phenomenon and deterioration of microwave characteristic, even when a ferrite member generates heat to raise a temperature thereof. The waveguide circulator is composed of a waveguide formed substantially in Y-shape with rectangular waveguides which are provided so as to position horizontally on a predetermined plane, and further they are extended in different three directions from junction positions of the waveguide wherein two ferrite members are placed in the junction positions thereof so as to oppose to each other on the upper and lower sides in the height direction perpendicular to the predetermined plane wherein an extended section extending in the height direction in the vicinities of the junction positions of the waveguides is formed, and a distance between the ferrite members is expanded to compensate decreased impedance.