A laser apparatus is provided with an optical element which is formed from a CaF2 crystal, which receives an ultraviolet laser beam obliquely entering one surface thereof, through which the ultraviolet laser beam transmits, and in which the electric field axis of a P-polarized light component, with respect to the surface, of the laser beam propagating thereinside coincides with one axis included in <111> of the CaF2 crystal. This method for manufacturing the optical element includes a step for cutting an ingot perpendicularly to a cutting axis, the ingot being formed by causing crystal growthof a seed crystal of CaF2 in one axial direction included in <111>, the cutting axis being defined as an axis that is inclined at an angle within the range of 14.18+-5 degrees from the direction of the crystal growth toward the direction of another axis which is included in <111> and is different from the axis in the direction of the crystal growth.