To provide a continuous casting method of steel by which steel containing REM is continuously cast without causing any blockage of a nozzle with inclusions.

The continuous casting method of steel containing 0.001-0.10 mass% of rare earth elements is provided which uses a sliding nozzle of two-layer or three-layer constitution as a flow rate adjusting mechanism of molten steel to be allowed to flow from a tundish to a casting mold through the nozzle. The opening of the sliding nozzle is adjusted under the condition that the opening area A of the sliding nozzle satisfies, during the casting, following expression (1): 0.9×Q+30≤A/A0≤75 wherein A0 denotes the opening area when the sliding nozzle is fully opened, Q[kg/s] denotes the throughput of the molten steel. A part of or the whole of a contact surface of the sliding nozzle with the molten steel is preferably constituted of a refractory containing MgO in an amount of ≥45 mass%.