A circuit member includes a metal base, an insulating layer, a conductor, and a cover layer. A terminal portion includes a thick portion formed on a side part of the insulating layer, and an extension portion, which is a part of the conductor, overlapping the thick portion. The extension portion includes a side pad portion along a side surface of the thick portion. A side surface of the side pad portion constitutes a side pad extending in a thickness direction of the conductor. A length of the side pad in a thickness direction is greater than a thickness of the conductor. A side pad insulating portion, which is formed of a part of the thick portion, is formed between a distal end of the metal base and the side pad portion.