A lubricant is provided for use in hot working such as cross-roll rolling of a seamless steel pipe. It effectively reduces the friction coefficient between the working tools and the material under the hot work, thus extending the lives of the tools. The lubricant contains: (A) from about 10 to about 60 wt % of alkali silicate; (B) from about 1 to about 20 wt % of silane coupling agent; (C) from about 0.1 to about 5.0 wt % of at least one kind of alkali compound selected from a group consisting of an alkali hydroxide, an alkali carbonate, an alkali borate and an alkali salt of mineral acid; and (D) from about 30 to about 70 wt % of water. Alternatively, the lubricant contains: (A) from about 10 to about 60 wt % of alkali silicate; (B) from about 1 to about 20 wt % of silane coupling agent; (C) from about 0.1 to about 5.0 wt % of at least one kind of alkali compound selected from a group consisting of an alkali hydroxide, an alkali carbonate, an alkali borate and an alkali salt of mineral acid; (D) from about 5 to about 50 wt % of water; (E) from about 10 to about 60 wt % of iron oxide; and (F) from about 0.1 to about 5.0 wt % of at least one additive selected from a group consisting of a dispersant and a thickening agent.