A piezoelectric resonator includes a piezoelectric resonator element having a base portion and a resonating arm extending from the base portion, a package including a bottom to which the piezoelectric resonator element is fixed and a frame wall that surrounds the bottom and having an opening above the bottom, and a lid for closing the opening of the package. In this piezoelectric resonator, the lid includes a main body having a through-hole formed therein, a flange formed to surround a periphery of the main body and to be thinner than the main body, and an optically transparent member located in the through-hole. The flange has a joining portion with an upper end surface of the frame wall, and the main body projects in a direction from the flange to the bottom in a thickness direction. Also, the through-hole is at a position displaced in a first direction approaching a first end of the main body from a center of the main body. Also, the flange is joined with the frame wall such that a clearance between the first end and the joining portion of the flange nearest to the first end is larger than a clearance between a second end in a second direction opposite to the first direction of the main body and the joining portion of the flange nearest to the second end.