The present invention provides an aptamer that binds to A disintegrin and metalloproteinase with thrombospondin motifs-5 (ADAMTS5). The aptamer includes a sequence that is represented by formula (1) or formula (2) (provided that the uracils may be thymines). (1) GGGGCCUCC-N1-GGACYAAACC. (2) GGGGCCUCC-N1-GGACWYAAACC. (In the formulas, N1 is 324 bases long, Y represents C or U, and W represents A or U.)