PURPOSE: To improve the moisture resistance and moisture proofness of an epoxy resin, by mixing it with a curing agent, an alkylarylsilsesquioxane silicone compound and lanolin.

CONSTITUTION: An epoxy resin is mixed with a curing agent, an alkylarylsilsesquioxane silicone compound of the formula (wherein R1WR6 are each alkyl or the like), and lanolin and/or its derivative. It is preferable from the viewpoint of curing properties that the mixing ratio of the above curing agent is such that the chemical equivalent ratio of the number of the functional groups of the curing agent to that of the epoxy groups of the epoxy resin lies within the range of 0.5W1.5. It is preferable that the above silicone compound is contained in an amount of 0.1W5pts.wt. per 100pts.wt. epoxy resin and that lanolin or its derivative is used in an amount of 0.1W10pts.wt. per 100pts.wt. epoxy resin.