The invention discloses a water-soluble lubricant for use in metal machining which comprises 0.01 mass percent to less than 5 mass percent of a organic carboxylic acid metallic salt (A), 0.05 mass percent to 20 mass percent of nonionic surface active agent (B) and water, wherein when 1g lubricant is weighted in a container with the bottom area of 50cm <2> and kept at a temperature of 100 DEG C in a thermostat, the needed time for evaporating the lubricant of 80 mass percent is within 10 minutes. The invention also discloses a metal machining method which basically comprises a step of coating the water-soluble lubricant dope for metal machining on at least either of a right side and a back side of a thin-wall metal plate and a step of machining the thin-wall metal plate by stamping and/or cutting. The invention also discloses metal machining equipment which basically comprises a clamping device for the thin-wall metal plate, a drive device for drawing out the thin-wall metal plate, a coating device for coating the water-soluble lubricant dope for metal machining on at least either of the right side and the back side of the thin-wall metal plate and a machining device for machining by stamping and/or cutting, wherein, the coating device is characterized by controlling the feeding rate of the water-soluble lubricant for coating the dope on the thin-wall metal plate.