A ferrite core includes an end face portion, a pair of outer legs protruding from the end face portion, and a center leg protruding from the end face portion between the pair of outer legs. A width W1 close to one end portion of the center leg in a Y-axis direction perpendicular to a facing direction of the outer legs is smaller than a width W2 close to the other end portion. According to this configuration, a circuit component may be positioned close to the end portion. A transformer includes the ferrite core.