A nonionic surfactant composition comprising: a nonionic surfactant that comprises a molecule having a C10-C22 alkyl group and/or alkenyl group as a hydrophobic group, a polyoxyalkylene chain as a hydrophilic group, no aromatic ring, no C9-C14 alkyl group derived from an alcohol that is produced from a higher olefin derived from a mixture of propylene and butene through an oxo process, and no C13 alkyl group derived from an alcohol that is produced from a higher olefin derived from a propylene tetramer through an oxo process, wherein the nonionic surfactant has a hydrodynamic radius of 5.0 to 8.0 nm at 40°C in an aqueous solution in which a nonionic surfactant concentration is 0. 1 kg/L in the nonionic surfactant composition, the radius being measured by a dynamic light scattering method, and wherein the nonionic surfactant comprises a nonionic surfactant represented by the formula: R 1 O(CH 2 CH 2 O) n1 H wherein R 1 is a C13 linear or branched alkyl group (except a C13 alkyl group derived from an alcohol that is produced from a higher olefin derived from a mixture of propylene and butene through an oxo process, and a C13 alkyl group derived from an alcohol that is produced from a higher olefin derived from a propylene tetramer through an oxo process), and n 1 is an integer of 5 to 15, and a nonionic surfactant represented by the formula: R 2 O(CH 2 CH(CH 3)O) m (CH 2 CH 2 O) n2 H wherein R 2 is a C10-C16 linear or branched alkyl group (except a C10-C14 alkyl group derived from an alcohol that is produced from a higher olefin derived from a mixture of propylene and butene through an oxo process, and a C13 alkyl group derived from an alcohol that is produced from a higher olefin derived from a propylene tetramer through an oxo process), n 2 is an integer of 5 to 20, and m is an integer of 1 to 6. a nonionic surfactant that comprises a molecule having a C10-C22 alkyl group and/or alkenyl group as a hydrophobic group, a polyoxyalkylene chain as a hydrophilic group, no aromatic ring, no C9-C14 alkyl group derived from an alcohol that is produced from a higher olefin derived from a mixture of propylene and butene through an oxo process, and no C13 alkyl group derived from an alcohol that is produced from a higher olefin derived from a propylene tetramer through an oxo process, wherein the nonionic surfactant has a hydrodynamic radius of 5.0 to 8.0 nm at 40°C in an aqueous solution in which a nonionic surfactant concentration is 0. 1 kg/L in the nonionic surfactant composition, the radius being measured by a dynamic light scattering method, and wherein the nonionic surfactant comprises a nonionic surfactant represented by the formula: R 1 O(CH 2 CH 2 O) n1 H wherein R 1 is a C13 linear or branched alkyl group (except a C13 alkyl group derived from an alcohol that is produced from a higher olefin derived from a mixture of propylene and butene through an oxo process, and a C13 alkyl group derived from an alcohol that is produced from a higher olefin derived from a propylene tetramer through an oxo process), and n 1 is an integer of 5 to 15, and a nonionic surfactant represented by the formula: R 2 O(CH 2 CH(CH 3)O) m (CH 2 CH 2 O) n2 H wherein R 2 is a C10-C16 linear or branched alkyl group (except a C10-C14 alkyl group derived from an alcohol that is produced from a higher olefin derived from a mixture of propylene and butene through an oxo process, and a C13 alkyl group derived from an alcohol that is produced from a higher olefin derived from a propylene tetramer through an oxo process), n 2 is an integer of 5 to 20, and m is an integer of 1 to 6.