The invention provides a method for preventing fouling in chemical equipment, comprising adding an antifouling agent which comprises a polyoxyalkylene polymer represented by the general formula (1) or the general formula (13) and having Mn of 30,000 or less to a component in the chemical equipment: (A: a group to which C 2 -C 20 olefins are polymerized; R 1 , R 2 , R 101 , and R 102 : H or a C 1 -C 18 alkyl group; X 1 and X 2 : a group represented by the general formula (2) or the general formula (4); E, E 101 , and E 112 : O or S; X 3 , X 7 , and X 8 : polyalkylene glycol group; R 3 : a hydrocarbon group; G: -OX 4 or -NX 5 X 6 (X 4 , X 5 , and X 6 : a polyalkylene glycol group); m: 1-10; A 101 : a group to which C 2 -C 20 olefms are polymerized; X 101 and X 102 : one represents a hydrogen atom or a group represented by the general formula (14) or the general formula (15), and the other represents a group represented by the general formula (16); R 104 : H, a hydrocarbon group, or an acyl group; R 105 and R 106 : hydrocarbon groups; and X 104 : a polyalkylene glycol group).