Disclosed are a light guide plate and a backlight unit. The backlight unit according to the present invention includes: a light guide plate; a light source disposed on one side of the light guide plate; and a reflective plate disposed under the light guide plate, wherein, in the cross section of one side of the light guide plate, the light guide plate includes a plurality of unit slits including a first slit and a second slit, wherein the first slit and the second slit are inclined from a top surface toward the inside of the light guide plate with respect to a vertical direction of the top surface, and wherein the first slit and the second slit are symmetrical to each other with respect to the middle portion of the unit slit.