A sensor unit with high reliability and stable detection accuracy against vibrations of an installation target object is to be provided.
A sensor unit includes: a sensor module configured including a substrate with inertial sensors mounted thereon, and an inner case in which the substrate is installed; and an outer case accommodating the sensor module. A recessed part is formed in the inner case. The inertial sensors are arranged in an area overlapping with the recessed part as viewed in a plan view seen from the direction of thickness of the substrate, and a filling member is provided to fill a space formed by the substrate and the recessed part. The sensor module is joined to a bottom wall of the outer case via a joining member.