We investigated the effect of film thickness on the superconducting properties of GdBa₂Cu₃O₇ (GdBCO) films on the SrTiO₃ (STO)(1 0 0) substrates which were fabricated using pulsed laser deposition (PLD) with a KrF exicmer laser (248 nm) pulses of 2.5 J/cm². With the target-to-substrate distance of 6.5 cm, GdBCO films were deposited at the substrate temperature of 810 °C in the oxygen pressure of 400 mTorr. Optimally processed GdBCO samples exhibited T_c of 91.3 K and J_c of 5.2 MA/cm² at 77 K in self field. When the film thickness increased from 0.15 to 2.2 μm, J_c values were decreased from 5.2 to 1.3 MA/cm². It was considered that the J_c reduction with increasing the thickness is attributed to the increase in the average size and density of particulates, leading to decrease in superconducting phase fraction, and also to the formation of cracks, reducing the supercurrent path.