A start-up method of a bubble column slurry bed reactor for producing hydrocarbons by the Fischer-Tropsch synthesis reaction in which reactor a heat removal line is installed, the method comprising: a first step of filling a slurry, in which a Fischer-Tropsch synthesis reaction catalyst particles are suspended in a slurry preparation oil, which is a hydrocarbon oil in which the sulfur content and the aromatic content are respectively 1 mass ppm or lower, the 5% distillation point is 120 to 270°C, and the 95% distillation point is 330 to 650°C, into the reactor, wherein the filling is performed such that a volume of a heavy oil component comprising components with a boiling point of 300°C or more of the hydrocarbon oil within the slurry filled into the reactor is 50% or more with respect to the volume of a void space in the reactor below the lowest end of the lowest heat removal line, and such that the height of the liquid surface of the slurry in the reactor is lower than the height at which airborne droplets of the liquid in the reactor begin to be carried by the gas flowing out from the outlet at the upper part of the reactor; and a second step of, in a state where synthesis gas that is primarily hydrogen and carbon monoxide is introduced into the slurry filled into the reactor, increasing the reaction temperature of the reactor, and starting the Fischer-Tropsch synthesis reaction, wherein the slurry preparation oil is the hydrocarbon oil within the slurry containing a light oil component comprising components with a boiling point of less than 300°C with an amount equal to or more than the volume of the light oil component in the slurry preparation oil which is necessary for the light oil component to be present as liquid in the reactor at 1 volume % or more of the hydrocarbon oil within the slurry when the carbon monoxide conversion rate of the Fischer-Tropsch synthesis reaction has reached 20 volume % in the second step. a first step of filling a slurry, in which a Fischer-Tropsch synthesis reaction catalyst particles are suspended in a slurry preparation oil, which is a hydrocarbon oil in which the sulfur content and the aromatic content are respectively 1 mass ppm or lower, the 5% distillation point is 120 to 270°C, and the 95% distillation point is 330 to 650°C, into the reactor, wherein the filling is performed such that a volume of a heavy oil component comprising components with a boiling point of 300°C or more of the hydrocarbon oil within the slurry filled into the reactor is 50% or more with respect to the volume of a void space in the reactor below the lowest end of the lowest heat removal line, and such that the height of the liquid surface of the slurry in the reactor is lower than the height at which airborne droplets of the liquid in the reactor begin to be carried by the gas flowing out from the outlet at the upper part of the reactor; and a second step of, in a state where synthesis gas that is primarily hydrogen and carbon monoxide is introduced into the slurry filled into the reactor, increasing the reaction temperature of the reactor, and starting the Fischer-Tropsch synthesis reaction, wherein the slurry preparation oil is the hydrocarbon oil within the slurry containing a light oil component comprising components with a boiling point of less than 300°C with an amount equal to or more than the volume of the light oil component in the slurry preparation oil which is necessary for the light oil component to be present as liquid in the reactor at 1 volume % or more of the hydrocarbon oil within the slurry when the carbon monoxide conversion rate of the Fischer-Tropsch synthesis reaction has reached 20 volume % in the second step.