Refined ethylene sulfite exhibits an excellent storage stability when used as a constituent of an electrolyte. A method of producing same has a step of reacting ethylene glycol and thionyl chloride to producing raw ethylene sulfite, a rectifying step for rectifying the raw ethylene sulfite, and a refining process for refining the raw ethylene sulfite or the rectified ethylene sulfite conducted before or after the rectifying step. The refining process is at least one process selected from the group consisting of a washing process, a dehydration process by total reflux distillation, a second rectifying process, and an absorbing process. Refined ethylene sulfite produced according to the method contains chloroethanol in an amount of not more than 1000 ppm.