A gas turbine blade has a trench part of a film cooling unit for cooling a blade part that is formed at a tip of a film cooling hole part. As a result, cooling efficiency of the blade can be improved since the blade part is sufficiently cooled even during introduction of a large amount of cooling air, durability of the blade can be increased by inhibiting the blade from being damaged due to hot gas since the trench part is formed to have a minimum width, and efficiency of a gas turbine can be increased by an improvement in film efficiency.