To provide a method of pressure measurement using a measuring apparatus which includes a crystal oscillator can prevent electrode parts of a crystal oscillator from corroding, keep natural resonance impedance stable and constant, and improve accuracy in measuring pressure or the like as well as reliability and life as a pressure measuring apparatus and the like.

The measuring apparatus provides the method of measurement on the basis of the measurement of the resonance impedance of the crystal oscillator 18 which varies according to pressure changes. The measuring apparatus used for the measurement includes both a protective case 20 with an opening part 20a for housing the crystal oscillator 18 inside and a protective cap 24 provided in relation to the opening part of the protective case for forming a gap 25 as a passage for moving and guiding active gaseous molecules to the opening part while generating collisions.