A physical quantity sensor has a package, which is provided with a substrate and a lid and has an internal space inside, and a functional element which is accommodated in the internal space, the lid is formed on a partition wall section which is provided on the periphery of the internal space in planar view and has a communication hole which causes a lower surface at the substrate side to communicate with an upper surface at the opposite side to the substrate, and the communication hole communicates with the internal space via a groove which is formed in the substrate.