Provided are an aptamer bound to chymase to inhibit activity of chymase； an aptamer containing a nucleotide sequence represented by X 1 GAUAGAN 1 N 2 UAAX 2 wherein X 1 and X 2 are the same or different and each is A or G, and N 1 and N 2 are the same or different and each is A, G, C, U or T； a complex containing the aptamer and a functional substance (e.g., affinity substance, labeling substance, enzyme, drug delivery medium, drug and the like)； a pharmaceutical or a reagent containing the aptamer or complex； a detection and a purification methods of chymase using the aptamer or complex and the like.
