In a method of forming an active pattern, a gate metal layer is formed on a base substrate. The gate metal layer is patterned to form a gate line, and a gate pattern spaced apart from the gate line. A gate insulation layer is formed on the base substrate including the gate line and the gate pattern thereon, to form a first protruded boundary surface corresponding to an area including the gate pattern. An amorphous semiconductor layer is formed on the base substrate including the gate insulation layer thereon, to form a second protruded boundary surface corresponding to the first protruded boundary surface. The amorphous semiconductor layer is crystallized by illuminating a laser to the amorphous semiconductor layer on the second protruded boundary surface.