To obtain a substance which gives a phororesist being capable of transmitting an argon fluoride excimer laser wavelength of a specified value and transparent and having good dry etching resistance by homopolymerizing or copolymerizing a monomer prepared by bonding a cholic acid, deoxycholic acid, or lithocholic acid derivative of an aliphatic polycyclic structure to norbornene with maleic anhydride or the like.

The laser wavelength is 193 nm. The monomer is represented by the formula (wherein R1 and R2 are each H, methyl substituted on norbornene, OH, CH2OH, CO2CH3, to the like; R3 is (CH2)nO, CO(CH2)nO, or the like; n is 0-3; R4 and R5 are each H, OH, OCOCH3, or the like; and R6 is H, C(CH3)3, tetrahydropyranyl protective group, or the like). This is obtained by converting the acid group of cholic acid or the like into a protective group which leaves when treated with an acid and reacting the converted compound with a norbornene derivative such as 2-chlorocarbonyl-5-norbornene. This monomer is homopolymerized or copolymerized with maleic anhydride or the like to obtain the odjective substance.