A circuit board includes a board body and pair of connection portions disposed at both ends of the board body. Each of the pair of connection portions is inserted into a connector. Each of the pair of connection portions includes a connection terminal electrically connected to the connector, and at least one of the pair of connection portions includes an extending portion extending from the connection terminal to an insertion leading end of the at least one of the pair of connection portion. The extending portion is disposed at a position to avoid a virtual line extending in an insertion direction through a position where the connector and the connection terminal are electrically connected.