Abstract: A positive photoresist composition comprising a polymer, a photoactived agent and an dissolution inhibitor represented by the following formula (1): wherein R1 and R2 each independently is a hydroxyl group, a C1-8 hydroxyalkyl group, or a C3-8 hydroxycycloalkyl group; R3, R4 and R5 each independently is a hydrogen, a C1-8 hydroxyalkyl group, a C1-6 carboxylic acid or a C3-8 carboxylic acid ester; k is an integer of 0, 1, 2, 3, 4, 5 or 6. The photoresist composition has high transparency to deep UV light and is capable of forming good fine patterns, roughness and high sensitivity, thus being useful as a chemically amplified type resist when exposed to deep UV light from an KrF and ArF excimer laser.