PURPOSE: To obtain a general-purpose photosensitive resin compsn. having transparency in the oscillation wavelength region of light of ultrashort wavelength such as ArF excimer laser light, provided with sensitivity (absorption) at longer wavelength by selecting a photosensitive agent such as an optical acid generating agent or introduced photosensitive groups, adaptable even to g-beams, i- beams and KrF excimer laser light and fit for fine working.

CONSTITUTION: This photosensitive resin compsn. contains cellulose resin contg. base resin having a structure crosslinked with an acetal or ketal skeleton and an optical acid generating agent, cellulose resin having a structure crosslinked with an acetal or ketal skeleton and provided with an optical acid generating function at the crosslinked part or cellulose resin crosslinked with an acetal or ketal skeleton and contd. groups having an optical acid generating function introduced into uncrosslinked parts.