An automotive lamp unit includes a bus bar unit forming a circuit with a plurality of bus bars connected with each other via a bridge portion, the bus bar unit including terminals, for connection to switches and a power source, and a supporting member for supporting a lamp, the circuit serving to switch on the lamp, and a resin base member provided with the bus bar unit mounted thereon at a predetermined position, and a small hole formed in the resin base member at a position thereof associated with the bridge portion. The plurality of bus bars are separated from each other at the bridge portion which is disposed in the small hole.