Abstract: Proposed is a positive- or negative-working chemical-sensitization photoresist composition having advantages in respect of the contrast and resolution of patterning, photo-sensitivity and cross sectional profile of the patterned resist layer as well as in respect of stability of the latent image formed by pattern-wise exposure to light before post-exposure baking treatment. The composition comprises: (A) 100 parts by weight of a film-forming resinous ingredient which causes a change, i.e. increase or decrease, of solubility in an aqueous alkaline solution by the interaction with an acid; and (B) from 0.5 to 20 parts by weight of a radiation-sensitive acid-generating agent which is a diazomethane compound represented by the general formulaR.sup.1 --SO.sub.2 --C(=N.sub.2)--SO.sub.2 --R.sup.2,in which R.sup.1 and R.sup.2 are each, independently from the other, a monovalent cyclic group substituted on the cyclic nucleus by an acid-dissociable group such as a tert-butoxycarbonyl and acetal groups.