The present invention provides an all-in-one type continuous reactor for preparing a positive electrode active material for a lithium secondary battery, the continuous reactor comprising: a flange unit 12 provided at one side of a cylinder 10; at least one reactant inlet port 13 provided on the flange unit so as to communicate with the reaction chamber 11 and configured to introduce a reactant into the reaction chamber; a reaction product outlet port 14 provided at the other side of the cylinder 10 so as to communicate with the reaction chamber 11 and configured to discharge a reaction product from the reaction chamber; a plurality of extra ports 15 provided between the reactant inlet port 13 and the reaction product outlet port 14 so as to communicate with the reaction chamber 11; a temperature control unit 40 disposed between the inner circumferential surface and outer circumferential surface 10, the temperature control unit 40 comprising a ring-shaped refrigerant chamber 41 and a refrigerant filled in the refrigerant chamber; a pulverizing unit 50 provided in the reactant inlet port 13 and configured to pulverize particles of the reactant that is introduced through the reactant inlet port; a flow rate sensor 60 provided in at least one of the reactant inlet port 13, the reaction product outlet port 14 and the extra ports 15 and configured to sense the flow rate of the reactant; and a flow rate control unit 70 configured to control the flow rate of the reactant, which is introduced through the reactant inlet port 13, on the basis of flow rate data sensed by the flow rate sensor 60.