A cleaning agent composition comprising a nonionic surfactant represented by the following formula (1): R1O(EO)x(PO)yH (I)(wherein R1 represents a linear or branched alkyl group having from 6 to 20 carbon atoms or a linear or branched alkenyl group having from 6 to 20 carbon atoms, EO represents an oxyethylene group, PO represents an oxypropylene group, EO and PO each is bonded by random addition or block addition, x number of EOs and y number of POs are arranged in an arbitrary order, x and y each independently represents an integer of 1 to 20, and x/(x+y) is 0.5 or more) and a quaternary ammonium hydroxide) is provided. Also, cleaning and production methods for semiconductor wafer using the cleaning agent composition and semiconductor wafer produced by the production method are provided.