A photoresist composition comprising an acid generator and a resin which comprises a structural unit having an acid-liable group, the acid generator generating an acid (I) or an acid (II): the acid (I) showing a hydrogen bonding parameter in the range of 12 (MPa)1/2 to 15 (MPa)1/2 and a polarity parameter in the range of 15 (MPa)1/2 or more; the acid (II) showing a hydrogen bonding parameter in the range of 12 (MPa)1/2 to 15 (MPa)1/2, and a distance of Hansen solubility parameters between the acid (II) and γ-butyrolactone being 7.5 or less, and the distance being calculated from formula (1): R=(4×(δdA−18)2+(δpA−16.6)2+(δhA−7.4)2)1/2  (1) in which δdA represents a dispersion parameter of an acid, δpA represents a polarity parameter of an acid, δhA represents a hydrogen bonding parameter of an acid, and R represents a distance of Hansen solubility parameters between an acid and γ-butyrolactone.