Disclosed is an aptamer that specifically binds to chymase to inhibit a chymase activity. Also disclosed is a complex comprising said aptamer and a functional substance (i.e., an affinity substance, a substance for labelling, an enzyme, a drug delivery vehicle or a drug). Further disclosed is the use of said aptamer in the manufacture of a medicament for use in the prevention of treatment of a cardiovascular disease or fibrosis. Also disclosed is a method of detecting or purifying a chymase using said aptamer or complex.
