Positive photoresist composition

A positive photoresist composition which comprises (A) a resin which contains a repeating unit represented by formula (I) shown below and a repeating unit represented by formula (II) shown below and whose solubility in an alkaline developing solution increases by the action of an acid and (B) a compound which generates an acid upon irradiation with an actinic ray or radiation,

• 37
• wherein R1, R2 and R3, which may be the same or different, each independently represents an alkyl group, a haloalkyl group, a halogen atom, an alkoxy group, a trialkylsilyl group or a trialkylsilyloxy group;
• and n represents 0 or 1,
• 38
• wherein M represents an atomic group necessary for forming an alicyclic structure, which may be substituted, together with the connected two carbon atoms (C-C) ;
• and R11 and R12, which may be the same or different, each independently represents a hydrogen atom, a cyano group, a halogen atom or an alkyl group which may be substituted.