An internal combustion engine fitted with a combustion pressure detection device includes: an internal combustion engine having a combustion chamber, a pressure detection device having a housing, a diaphragm, and a detection member, and having a shoulder part. The material diffracts radiation in a first wavelength band when the material is at a first temperature and the material diffracts radiation in a second wavelength band when the material is at a second temperature. A sidewall of the recess is then altered.