Method and apparatus for exposing a substrate

A substrate exposure method and apparatus is provided to reduce a time required for an exposure process by projecting light of two patterns onto a substrate by using one polarizing mask, and to prevent the two patterns from mis-aligning. Two projection lights having different pattern information are generated from one polarizing mask(S100), and then the projection lights are projected onto a substrate along different light paths(S200). The step of generating the projection lights includes irradiating the light onto the polarizing mask and dividing the light projecting on the polarizing mask into two projection lights according to a polarizing mode.