A capacitor holder comprises: a holding portion having a cylindrical inner wall surface, at least an outer peripheral portion of the inner wall surface being open, the holding portion being configured to hold a capacitor inserted through the opening into an inside of the inner wall surface; a fixed portion formed integrally with the holding portion and positioned opposite to the opening of the holding portion; a pair of fitting grooves formed at a pair of end surfaces of the fixed portion opposed to each other adjacent to the holding portion, the fitting grooves being configured to fittably engage with end edges of a printed circuit board to extend along a surface of the printed circuit board; and a proximity suppressor configured to suppress portions of the fixed portion where the fitting grooves are formed from being brought into proximity each other.