PHYSICAL QUANTITY MEASUREMENT DEVICE

Provided is a physical quantity measurement device capable of preventing a sealing of a cavity portion on a back surface side of a diaphragm of a thermal air flow rate sensor while improving measurement accuracy of the thermal air flow rate sensor as compared with the related art. A physical quantity measurement device includes a lead frame having a mounting surface f on which a flow rate sensor which is the thermal air flow rate sensor is mounted, and a flow passage forming member disposed on a back surface f opposite to the mounting surface f of the lead frame . A ventilation flow path is formed by a first through hole provided in the lead frame and communicating with a cavity portion of the flow rate sensor a second through hole provided in the lead frame and opened in the mounting surface f and a connection flow path that is defined between the lead frame and the flow passage forming member and connecting the first through hole and the second through hole