A physical quantity measuring device includes: a metallic cylindrical case; a sensor module configured to detect a physical quantity; a synthetic-resin joint provided near a first open end of the cylindrical case, the joint being attached with the sensor module and provided with an introduction port for introducing a measurement target fluid; and a cover provided near a second open end of the cylindrical case. The cover includes a locking portion for locking the sensor module. The cylindrical case includes an engagement portion provided near the first open end and engaged with the joint and a crimp portion provided near the second open end, the crimp portion configured to be plastically deformed by crimping. The cover is attached to the cylindrical case by crimping the crimp portion.