The porous poly(vinyl alcohol) (PVA)-poly(vinyl acetate) (PVAc) composite film prepared by acetone extraction from a PVAc latex film containing PVA was colored in organic solvents for PVAc having a refractive index close to that of PVA, The scattered color changed from yellow to green through orange, red, purple, and blue with an increase in the refractive index of the solvents. The coloration phenomena were based on the intersection between the dispersive curve of PVA and that of the solvents for PVAc in the visible region. If a mixed organic solvent of a solvent and a nonsolvent for PVAc was used, the porous film easily exhibited a color change when it was placed between two glass plates which were pressed together using paper clips, When the refractive index of the solvent was higher than that of the nonsolvent, the scattered color changed from yellow to blue with increasing pressure, and when the refractive index of the solvent was lower than that of the nonsolvent, the scattered color conversely changed from blue to yellow. This mechanism was found to involve a very simple phenomenon in which PVAc grafted on the surfaces of the spherical PVA cells selectively absorbs the solvent from the mixed solvent, and the nonsolvent remaining in the PVA cells is forced out of the porous film with increasing pressure. This piezochromism can be controlled by the refractive index of the mixed solvent, the selection of the solvent and the nonsolvent for PVAc, and the pressure gradient.