To provide a transformer, in which the creeping distances between a transformer core and transformer pins can be secured sufficiently, without having to increase the size of the transformer.

A creeping distances L from the transformer pins 6 to the transformer core 3 through the upper surface of a substrate 7 and the insides of the leg sections 5 of a bobbin are fully secured by forming gaps 10 by cutting the surfaces of the leg sections 5, facing the core 3 upward from the substrate side 7.