The present invention relates to a photoresist composition containing Photo Base Generator (PBG), more specifically, to a photoresist composition which comprises (a) photoresist resin, (b) photo acid generator, (c) organic solvent and further (d) photo base generator. The photo base generator is preferably selected from benzyloxycarbonyl compound of Chemical Formula 1 or O-acyloxime compound of Chemical Formula 2, which prevents a slopping pattern formation and a severe I/D Bias occurrence. wherein, R′, R1 to R6 are defined in accordance with the Specification.