To obtain a cleaning agent composition containing a mixed isooctane composition having a boiling point falling within a specific range and dimethyl carbonate at respectively specific ratios, having low toxicity and excellent dryability and stain-removing performance and giving a highly cleaned product.

This composition is composed of (A) 20-50wt.% of a mixed isooctane composition having a boiling point of 113-116°C and (B) 50-80wt.% of dimethyl carbonate. The composition forms a pseudo-azeotropic mixture. A composition composed of 25.1wt.% of the component A and 74.9wt.% of the component B forms an azeotropic composition. The component A is preferably a mixture of about 70wt.% of 2,3-dimethylhexane as a main component, about 20wt.% of 2-methyl-3-ethylpentane and about 10wt.% of 2,3,4- trimethylpentane. The cleaning agent composition is impregnated in a fibrous material and the surface of a cleaning object is wiped with the material.