Disclosed is a circuit unit with a novel structure that can counter the heat generation by resistors while suppressing an increase in size and cost of the circuit unit. A circuit unit includes a wiring member, a lower case that holds the wiring member, an upper case that covers the lower case, and resistors connected to the wiring member, wherein the upper case include wall portions that surround peripheries of the resistors, and wherein, in a first orthogonal direction orthogonal to the longitudinal direction of the resistors, the separation distance between intermediate portions in the longitudinal direction of the resistors and the wall portions of the upper case is greater than the separation distance between end portions in the longitudinal direction of the resistors and the wall portions of the upper case.