To provide a measuring apparatus including a crystal oscillator capable of preventing electrode parts of the crystal oscillator from corroding, keeping natural resonance impedance stable and constant, and improving accuracy in measuring pressure or the like and reliability and life as a pressure measuring apparatus and the like.

The measuring apparatus is used for performing a measurement on the basis of the measurement of the resonance impedance of the crystal oscillator 18 which varies according to pressure changes, comprising both a protective case 20 having 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.