A physical quantity sensor-fixing structure includes a holder holding a physical quantity sensor including a detection unit to detect a physical quantity and a plurality of lead wires connected to the detection unit. The holder fixes the physical quantity sensor to a plurality of conductive support members to be respectively connected to the plurality of lead wires. The holder includes a main body member including a housing portion to house at least a portion of the physical quantity sensor, and a lid member covering at least a portion of the housing portion.