A method for producing a composition containing a latex of a nitrile rubber of α,β-ethylenically unsaturated nitrile monomer unit of 8 to 60 wt % content, and an iodine value of 120 or less, an isothiazoline-based compound represented by formula (1), and a benzisothiazoline-based compound represented by formula (2), both in a content of 26 ppm by weight or more to the rubber, wherein adding both compounds to the latex at 2,000 ppm by weight/min or less, at 50° C. or lower, and the compounds in an aqueous state having 0.1 to 40 wt % concentration. formula (1), R1 and formula (2), R4 represents a hydrogen atom, or a substituted or unsubstituted organic group; wherein formula (1) R2 and R3 represent a hydrogen atom, a halogen atom, or an substituted organic group; and formula (2), R5 represent a hydrogen atom, or an substituted organic group, and an integer “n” of 0 to 4.