A power-supply device including: a casing having a space therein and formed by metal stamping or having a thickness ranging from 0.3 to 3.0 mm; and a circuit board disposed inside the casing, wherein the casing includes a casing portion having an opening, and a cover portion disposed to cover the opening of the casing portion, the casing portion has a through hole formed at a position corresponding to a connector terminal connected to the circuit board, and the cover portion includes a storage portion bulging outward from the casing, the storage portion storing either one of an electronic component provided to a face of the circuit board which faces the cover portion and an electronic component provided across the circuit board.