Disclosed are a two-dimensional semiconductor in which an energy band gap changes with thickness, a manufacturing method therefor, and a semiconductor device comprising the same. A two-dimensional semiconductor according to an embodiment comprises: a first layer having a first thickness; and a second layer having a second thickness, wherein the first thickness and the second thickness are different from each other, the first layer forms a first junction with a first electrode, and the second layer forms a second junction with a second electrode.