Solvolysis reaction was observed to proceed the esterification of cinnamoyl chloride and water-based cellulose reaction system. A negative type photoresist might be produced including a side product of HCl, in theory. Ethyl alcohol(or methyl alcohol) was added to intermix the two separated reactant solutions which were composed of a reactant and a solvent in each liquid phase, i.e., cinnamoyl chloride in toluene and HEC(hydroxyethyl cellulose) in water. As a result, a negative type photoresist was obtained and some amount of solvolysis was inevitable.