Abstract: An object of the present invention is to provide a technique for preventing or treating HTLV-1-associated diseases, such as ATL, a material for use in the technique, a method for screening the material, and the like. The present invention provides a TCR screening method comprising sorting HTLV-1-derived antigen-recognizing cells from cells derived from an HTVL-1 patient and subjecting the HTLV-1-derived antigen-recognizing cells to TCR repertoire analysis, ranking the TCR types in descending order of the number of cells of each TCR type, and selecting a highly ranked TCR. The present invention provides a prophylactic or therapeutic agent for an HTLV-1-associated disease, the agent comprising a TCR comprising specific CDRs that can be obtained by the TCR screening method and cells expressing the TCR.