The transformer includes a bobbin, a plurality of terminal electrode, a primary coil, a secondary coil, and a hook part. The bobbin includes a core portion extending in an axial direction, and terminal bases fixed at both ends of the core portion in the axial direction. The plurality of terminal electrode regions is provided on the terminal bases. Each terminal electrode region is provided with a wire connection part. The primary coil comprises a plurality of primary wires. The secondary coil comprises a plurality of secondary wires. The hook part is disposed between the core portion and one of the terminal electrode regions and configured to hook at least one of the primary wires and the secondary wires.