Polyethylene glycol for use in fields with application to a living body wherein the sum of the contents of ethylene glycol and diethylene glycol in the polyethylene glycol is less than or equal to that expressed in the following formula [I]: Sum ⁢   ⁢ of ⁢   ⁢ ethylene ⁢   ⁢ glycol ⁢   ⁢ and ⁢   ⁢ diethylene ⁢   ⁢ glycol ⁢   ⁢ contents ⁢   ⁢ ( ppm ) = 150 × 2900 × 0.85 ( x - 150 ) / 44 x [ I ] wherein x represents the average molecular weight of the polyethylene glycol, and the polyethylene glycol has an average molecular weight ranging from 190 to 1,050.