Provided is a turbine blade of a gas turbine including a turbine blade part having an airfoil shape including an internal cavity therein, a cast tip disposed at an upper portion of the turbine blade part, and a braze joint to attach the turbine blade part and the cast tip to each other. The turbine blade part and the cast tip has substantially the same cross-sectional shape in a top plan view. In addition, the turbine blade part further includes a protrusion disposed at a surface where the turbine blade part is attached to the cast tip. In a similar manner, the cast tip may have a concave portion at a surface where the cast tip is attached to the turbine blade part to allow the concave portion to be coupled to the protrusion of the turbine blade part.