Disclosed is a method of forming a hole in a glass substrate by using a pulsed laser, the method including (1) preparing the glass substrate including a first surface and a second surface that face each other; (2) forming a concave portion on the first surface by irradiating, with a first condition, the pulsed laser onto the first surface of the glass substrate through a lens; and (3) forming the hole by irradiating the pulsed laser onto the concave portion with a second condition such that energy density of the pulsed laser is less than or equal to a processing threshold value of the glass substrate.