To provide a washing liquid composition for washing molds, tools and ancillary facilities such as blending pot and pipe stained with resin for optical part, giving little influence on the environment, having little restriction on handling and exhibiting sufficient cleaning power.

The washing liquid composition for a resin for optical parts contains at least one compound selected from amides and imidazolidinones and a sulfoxide compound preferably at a weight ratio of 3/17 to 17/3. The amides and imidazolidinones are especially preferably dialkylformamide, dialkylacetamide, N-alkylpyrrolidone or dialkylimidazolidinone, the sulfoxides are preferably dialkylsulfoxide and the resin for optical parts is especially preferably an episulfide resin.