A method for determining a progression of rheumatoid arthritis in a subject or determining a therapeutic effect of a therapeutic drug for rheumatoid arthritis using a rheumatoid arthritis linked indicator in a subject, comprising: measuring an amount of expression of the FAM20A gene in peripheral blood derived from the subject; a) comparing the measured amount of expression of the FAM20A gene in the peripheral blood derived from the subject with a gene expression profile that is prepared based on an amount of expression of the FAM20A gene in peripheral blood collected from a patient with rheumatoid arthritis, when a progression of rheumatoid arthritis in a subject is determined; or b) comparing the measured amount of expression of the FAM20A gene in the peripheral blood derived from the subject after administration of a therapeutic drug with a gene expression profile that is prepared based on an amount of expression of the FAM20A gene in peripheral blood collected from the subject prior to administration of the therapeutic drug, when a therapeutic effect of a therapeutic drug for rheumatoid arthritis is determined, and wherein said gene expression profile shows a positive correlation between an amount of expression of the FAM20A gene and an indicator of a progression of rheumatoid arthritis in a subject; estimating the value of the indicator in the subject on the basis of the comparing step; and determining a progression of rheumatoid arthritis in a subject or determining a therapeutic effect of a therapeutic drug for rheumatoid arthritis from the estimated value of the indicator. measuring an amount of expression of the FAM20A gene in peripheral blood derived from the subject; a) comparing the measured amount of expression of the FAM20A gene in the peripheral blood derived from the subject with a gene expression profile that is prepared based on an amount of expression of the FAM20A gene in peripheral blood collected from a patient with rheumatoid arthritis, when a progression of rheumatoid arthritis in a subject is determined; or b) comparing the measured amount of expression of the FAM20A gene in the peripheral blood derived from the subject after administration of a therapeutic drug with a gene expression profile that is prepared based on an amount of expression of the FAM20A gene in peripheral blood collected from the subject prior to administration of the therapeutic drug, when a therapeutic effect of a therapeutic drug for rheumatoid arthritis is determined, and wherein said gene expression profile shows a positive correlation between an amount of expression of the FAM20A gene and an indicator of a progression of rheumatoid arthritis in a subject; estimating the value of the indicator in the subject on the basis of the comparing step; and determining a progression of rheumatoid arthritis in a subject or determining a therapeutic effect of a therapeutic drug for rheumatoid arthritis from the estimated value of the indicator. a) comparing the measured amount of expression of the FAM20A gene in the peripheral blood derived from the subject with a gene expression profile that is prepared based on an amount of expression of the FAM20A gene in peripheral blood collected from a patient with rheumatoid arthritis, when a progression of rheumatoid arthritis in a subject is determined; or b) comparing the measured amount of expression of the FAM20A gene in the peripheral blood derived from the subject after administration of a therapeutic drug with a gene expression profile that is prepared based on an amount of expression of the FAM20A gene in peripheral blood collected from the subject prior to administration of the therapeutic drug, when a therapeutic effect of a therapeutic drug for rheumatoid arthritis is determined, and wherein said gene expression profile shows a positive correlation between an amount of expression of the FAM20A gene and an indicator of a progression of rheumatoid arthritis in a subject; estimating the value of the indicator in the subject on the basis of the comparing step; and determining a progression of rheumatoid arthritis in a subject or determining a therapeutic effect of a therapeutic drug for rheumatoid arthritis from the estimated value of the indicator.