We prepared colloidal crystals immobilized in copolymer hydrogel films composed of N-isopropylacrylamide (NIPAM) and N-methylolacrylamide (NMAM) at various mixing ratios and examined the dependence of the degree of swelling and optical stop-band wavelength on ethanol concentration. Colloidal crystals immobilized in NIPAM-rich gels shrank considerably at low ethanol concentrations owing to the cononsolvency of NIPAM in the solvent. The optical stop-band wavelength changed significantly according to the change in the degree of swelling. In contrast, colloidal crystals immobilized in NMAM-rich gels shrank considerably at high ethanol concentrations owing to the nonsolvency of NMAM, resulting in a large shift of the stop-band wavelengths to lower values. These materials also exhibited thermosensitivity and are therefore potentially useful as tunable photonic crystals controlled by multiple stimuli and as sensors for detecting changes in a specific environment.