A liquid sealing agent used for automobile parts, electric parts, various kinds of machine parts and the like has encountered a problem that it is difficult to combine good oil resistance, heat resistance, adhesiveness and flexibility. The present invention provides a liquid gasket which improves these problems, and a material thereof. In the present invention, it is used a vinyl polymer which has at least one crosslinkable silyl group and can yield a cured product exhibiting an oil resistance superior to that of a cured product from a polymer obtained by replacing the repeating unit thereof with butyl acrylate alone, in any one item of the immersion test according to JIS K 6258 for the land use 3-5 lubricating oil specified in JIS K 2215.