To provide a wire connection structure not using connector, prevented from wire disconnection.

Core wires exposed at the terminal part of covered wires 50 are connected to a plurality of conductive connection pieces 30 protruded from a supporting part 22 by soldering. For the above, a wire holding part 40, composed of a holding part 42 holding the covered wires 50, having wire insertion holes 43 into which, the covered wires 50 are inserted, a mounting part 44 extending from the holding part 42 toward the supporting part 22 and mounted to the supporting part 22, and partitioning walls 45 partitioning respective connection pieces 30, is installed.