An object of the present invention is to provide a compound or a salt thereof having anti-HBV activity, a pharmaceutical composition, an anti-hepatitis B virus agent, a production inhibitor of DNA of a hepatitis B virus, and a production or secretion inhibitor of a hepatitis B surface antigen. According to the present invention, provided are a compound represented by General Formula [1] or a salt thereof:(in the formula, R1 represents a benzothiazolyl group which may be substituted (in which a carbon atom constituting the 6-membered ring of the benzothiazolyl group of R1 is bonded to the nitrogen atom of the pyridone ring)； R2 represents a C2-6 alkenyl group which may be substituted, or the like； and R3 represents a hydrogen atom or the like).
