To provide a photosensitive composition for metal or metal oxide etching excellent in resolution and etching resistance as a resist and ensuring enhanced product quality.

The photosensitive composition is applied to an object, at least the surface of which comprises a metal or metal oxide to be etched, and the composition is patternwise exposed with active energy beams and developed with a water-base developer to form a mask for etching, which can be removed with an alkali solution after the metal or metal oxide is etched. The composition contains A) a water-soluble photopolymerizable polymer containing constitutional units of formulae (I)-(III) (where X is one or more selected from H, an alkali metal and ammonium), B) at least one of a photopolymerization initiator and a photosensitizer and C) water as essential components.