An oscillator includes a package having a plurality of external terminals disposed on a mounting surface, a circuit element housed in the package, and a resonator which is housed in the package, and is electrically coupled to the circuit element, wherein the circuit element is electrically coupled to the package with a plurality of pads each of which is bonded to the package via a bump member, the circuit element has a rectangular shape in a plan view, and at least three of closest ones to four corners of the circuit element out of the bump members are bonded to the package at respective positions overlapping the plurality of external terminals in the plan view.