Abstract: A method for cutting off a steel plate, wherein the steel plate is heated to a temperature within the range of from 950.degree. to 1,400.degree. C. at the time of cutting off the steel plate; the heated steel plate is placed on a roller table extending horizontally and positioned at a desired position so that a side edge of the heated steel plate is in contact with the cutting edge of at least one cutting knife on the roller table. The cutting edge angle of the cutting knife is within the range of from 10.degree. to 45.degree.. The cutting knife is then moved horizontally relative to the heated steel plate, in the width direction or the length direction of the steel plate, at a cutting speed of from 10 to 1000 cm/minute, thereby cutting off the steel plate by the cutting knife in the horizontal direction.