A housing structure of a planar resistor is provided, wherein electrode extraction ends (4) of the planar resistor are on the same side of the resistor. A housing structure body (1) is made of an insulating material covering the surface of the resistor. An insulating structure (3) having a groove opening facing toward or away from the resistor is provided around each electrode extraction end (4) of the resistor. The insulating structure (3) is configured to be a multi-tooth or multi-groove insulating structure. Compared with the prior art, a structure having teeth or slots increases the surface creepage distance of an insulating material between two electrodes. Since the electrodes are mounted toward different directions, and a multi-groove opening is designed to face inward or outward, dust and dirt can hardly enter the resistor, so that the operating reliability and maintenance-free property of the resistor are improved.