Effects of high pressure treatment on the structure of connectin, one of the elastic protein of muscle were investigated by spectrometric analyses. Circular dichroism spectra show abundance of β-structure in the secondary structure of connectin, whereas α-helix content was less than 10%. No significant change in secondary structure was observed in the connectin pressurized up to 400 MPa, but significant decrease of β-sheet and increase of turn were observed in the connectin pressurized at 600 MPa. From the measurements of fluorescent spectra and center of spectral mass, it seems that the changes in the tertiary structure of connectin induced by relatively mild pressure of 100~200MPa were reversible, but the changes become irreversible with more higher pressure applied.