This paper describes the behaviour of chip in the case of steel cutting for the use of the design of chip breaker, and contains the following two parts. The first half describes the flow-out angle of chip, and that the values for the flow-out angle of chip calculated by the approximate theoretical equations accord with the measured values for various cutting conditions and tool designs, so that the authors draw up the nomograph for the flow-out angle of chip on the basis of the theoretical equations. The latter half describes the chip classification and the effect of cutting conditions on the shape of chip.