A photoresist composition containing a polymer having a structural unit including an acid-labile group, and a compound represented by the formula (1). In the formula (1), R1 represents a hydrogen atom or a monovalent acid-labile group. R2 represents an alicyclic hydrocarbon group having 3 to 20 carbon atoms and a valency of (m+1). m is an integer of 2 to 5. R3 and R4 each independently represent a hydrogen atom, a fluorine atom, a monovalent hydrocarbon group having 1 to 20 carbon atoms or a monovalent fluorinated hydrocarbon group having 1 to 20 carbon atoms. n is an integer of 0 to 5. At least two of a plurality of R1s optionally taken together represent a ring structure, together with a plurality of oxygen atoms bonding to R1 and the carbon atom(s) constituting R2 and bonding to these oxygen atoms. M+ represents a monovalent radiation-degradable onium cation.