To provide an electron beam or X-ray resist composition having high sensitivity and high resolving power, excellent in PCD and capable of giving a pattern profile excellent in rectangularity.

In the positive type electron beam or X-ray resist composition containing (a) a compound which generates an acid when irradiated with electron beams or X-rays and (b) a resin having a group which is decomposed by the action of the acid and increases solubility in an alkali developing solution, the compound (a) contains a specified sulfonic ester and a specified onium sulfonate.