PURPOSE: To compensate the unbalance due to a residue of etching, by providing the level diffferences of different heights in the width direction at both sides of a tuning fork type quartz oscillator consisting of two oscillating arms and a basement.

CONSTITUTION: A tuning fork type quartz oscillator 1 containing two oscillating arms 5, 5' and a basement 2 is formed out of a quartz thin plate by a lithography process. In this case, a so-called residue of etching is caused on the side face of the oscillator 1 to cause an unbalanced tuning fork. In this connection, the level differences 3 and 3' are provided in the width direction at both sides of the basement 2. The heights w1 and w2 of the levels 3 and 3' are set different from each other to compensate the unbalance of the tuning fork.