To provide a crystal device in which a small-sized crystal element can be mounted.

A crystal device comprises a substrate 110a, a recess SP, a conductive adhesive 140, and a crystal element 120. The substrate 110a is rectangular, includes a mount region R1 in the center and includes peripheral regions R2 at both sides of the mount region R1. The recess SP is provided in one of the peripheral regions R2 of the substrate 110a and has a polygonal shape in a plan view, the width in a direction along one side of the substrate 110a corresponding to one of the peripheral regions becoming narrower from the one of the peripheral regions R2 toward the mount region R1, and an apex at a side of the mount region R1. The conductive adhesive 140 is provided in the polygonal recess SP and is formed correspondingly to the shape of the recess SP. A crystal element 120 is connected onto an apex of the conductive adhesive 140 at a side of the mount region R1 while overlapping from the apex to the mount region R1.