An X-ray mask comprises an absorber pattern composed of a material capable of absorbing X-ray, a mask substrate for supporting the absorber pattern, composed of a material capable of transmitting X-ray, and a support frame for supporting the mask substrate, wherein the mask substrate is composed of a mask substrate material whose impurity content is suppressed to reduce positional distortions generated by X-ray radiation. Generation of positional distortions by X-ray exposure is inhibited and an arrangement of mask pattern can be ensured with a high precision.