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 a non-flat portion is provided to a region having a size greater than or equal to an outside diameter of a connector of an external connector line connected to the connector terminal in the casing portion.