A start-up method of a bubble column slurry bed reactor for producing hydrocarbons includes: a first step that fills into a reactor a slurry in which a Fischer-Tropsch synthesis reaction catalyst particles are suspended in a slurry preparation oil with a 5% distillation point of 120 to 270° C., a 95% distillation point of 330 to 650° C., and a sulfur component and an aromatic component of 1 mass ppm or less, and a second step that, in a state where synthesis gas that is primarily hydrogen and carbon monoxide is introduced into the slurry filled into the reactor, raises the temperature of the reactor and starts the Fischer-Tropsch synthesis reaction. As the slurry preparation oil, one containing predetermined components in preset amounts is used. In the first step, the slurry is filled into the reactor in an amount in which airborne droplets do not flow out.