A physical quantity measurement device measures a physical quantity of a fluid. A detection unit has a physical quantity detector that detects a physical quantity of the fluid in a measurement flow channel. A housing accommodates at least a part of the detection unit and forms the measurement flow channel. The housing includes a housing attachment that is attached to a predetermined attaching target, and a position holder holding a position of the detection unit by contacting the detection unit. The housing includes an inward part positioned inward of the attaching target and an outward part positioned outward of the attaching target. The position holder is provided inward of the housing attachment in an alignment direction along which the inward part and the outward part are aligned.