We investigate the temporal change of crustal structure around Iwate volcano, northeastern Japan, using calculations of the cross-correlation coefficients of P- and S-waves of pairs of similar earthquakes that occurred between 1995--2002 at the subducting Pacific Plate boundary. While large coefficients are observed at most stations throughout the period, two stations located on the southwestern slope of Iwate volcano exhibit small S-wave coefficients. The coefficients at these two stations decreased remarkably from 1998, corresponding to a period of significant volcanic activity and an M6.1 earthquake. Since 2000, the coefficients have recovered gradually, suggesting their correlation with the activity of Iwate volcano. The coefficients of P-waves at these stations are large compared to those of S-waves, suggesting that temporal change in the crustal structure beneath these stations occurred in elastic properties to which S-waves are sensitive, such as rigidity, related to magmatic and/or seismic activity in and around the volcano.