A laser processing apparatus and a stack processing apparatus are provided. The laser processing apparatus includes a laser oscillator and an optical system for forming a linear beam and an x-y-θ or x-θ stage. With use of the x-y-θ or x-θ stage, the object to be processed can be moved and rotated in the horizontal direction. With this operation, a desired region of the object to be processed can be efficiently irradiated with laser light, and the area occupied by a chamber provided with the x-y-θ or x-θ stage can be made small.