The present invention relates to: a catalyst activation method for Fischer-Tropsch synthesis; a catalyst regeneration method for Fischer-Tropsch synthesis; and a method for producing a liquid or solid hydrocarbon by using the Fischer-Tropsch synthesis reaction. The temperatures required for a metal carbide producing and activating reaction is markedly lower than existing catalyst activation temperatures, and the catalyst can be activated under conditions that are the same as Fischer-Tropsch synthesis reaction conditions, and thus there is no need for separate reduction equipment in the reactor, and a Fischer-Tropsch synthesis catalyst which has been used for a long time can be regenerated within the reactor without the catalyst being isolated or extracted from the reactor.