Disclosed is a water-soluble and oil-soluble oil solution, which enables to have excellent feeling of use without making the skin greasy when applied thereto. Also disclosed are a lubricant, a moisture-retaining agent and a preparation for external application, each containing such an oil solution. Specifically disclosed is an oil solution containing a dibasic acid ester compound represented by the following general formula (I). In the formula (I), R 1 represents an optionally substituted alkylene group having 2-4 carbon atoms； R 2 and R 3 independently represent an optionally substituted alkyl group having 1-4 carbon atoms； and n and m independently represent an integer of 0-4, with m + n being not less than 1 (excluding the case when both R 2 and R 3 are ethyl groups and both n and m are 1).
