A piezoelectric resonator unit that includes a piezoelectric resonator; a substrate that includes a mounting surface, an electrode pattern on the mounting surface; and a cap joined to the mounting surface of the substrate by a joining material such that the piezoelectric resonator is hermetically sealed. The electrode pattern includes a connection electrode to which the piezoelectric resonator is connected, and an extended electrode that is extended from the connection electrode towards an outer edge of the mounting surface. A joining region on the mounting surface is provided over an entire periphery and surrounds the connection electrode. An insulating material is in the joining region such that at least part of the electrode pattern is exposed therefrom.