The present invention provides a method of predicting and determining a therapeutic effect (especially whether complete remission is reached) or the level of improvement prior to administration of a biological formulation such as an anti-IL-6 agent or an anti-TNF-α agent, which is simple and cost-effective, and accurate. Sgp130, IP-10, sTNFRI, sTNFRII, GM-CSF, IL-1β, IL-2, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-12, IL-13, IL-15, Eotaxin, VEGF, MCP-1, TNF-α, IFN-γ, FGFbasic, PDGF-bb, sIL-6R, MIP-1α and the like can be utilized as a specific marker used in the method. Since a therapeutic effect (level of improvement in a symptom or possibility of remission) on a rheumatoid arthritis patient can be determined prior to the administration of a biological formulation using such a specific marker, rheumatoid arthritis therapy is possible at a precision that could not be achieved conventionally.