A physical quantity measuring device includes: a sensor module provided with a diaphragm; a joint to which the sensor module is attached, the joint including a pressure inlet for delivering fluid to be measured to the sensor module. The joint is made of a synthetic resin and includes a joint body and an elastically deformable claw provided to the joint body and configured to lock the sensor module. Since the claw keeps the sensor module to be held by virtue of the elastic force of the claw, a further attachment process such as welding for attaching the sensor module to the joint is unnecessary. Since the joint body and the claw are integrally made of synthetic resin, it is not necessary to separately manufacture the joint body and the claw.