Solvation dynamics at the water/mica interface was investigated by time-resolved fluorescence spectroscopy. Time-resolved fluorescence spectra of a coumarin dye immobilized on the mica surface show dynamic Stokes shifts with several hundreds picosecond time scale. Solvent relaxation time observed at the water/mica interface was remarkably longer than that observed in a bulk solution, suggesting existence of a rigid water layer on the mica surface, that is, hydrogen-bonding network is strongly formed at the mica surface.