Modified peptide or a pharmaceutically acceptable salt thereof, wherein the modified peptide has a structure represented by the formula of one of the following compounds 2-1, 2-3, 2-10, 2-11, 2-12, 2 -13, 2-14, 2- 15, 2-16, 2-25, 2-26, 2-27, 2-29, or 2-30: ** (See formula) ** in which hANP is hANP (1-28) consisting of the amino acid sequence of SEQ ID NO: 1 and is attached at the N-terminal end of the amino acid sequence to the linker structure through an amide bond； AG (5) is a sugar substance represented by the following formula ** (See formula) ** in which Gxx is GlcNAc and "O / N-L" represents the binding to the connective structure through an O-glucosidic bond； AG (7) is a sugar substance represented by the following formula ** (See formula) ** in which Gxx is GlcNAc and "O / N-L" represents the binding to the connective structure through an Oglucosidic bond； AG (9) is a sugar substance represented by the following formula ** (See formula) ** in which Gxx is GlcNAc and "O / N-L" represents the binding to the connective structure through an Oglucosidic bond； and SG is a sugar substance represented by the following formula ** (See formula) ** in which Gxx is GlcNAc and "O / N-L" represents the binding to the connective structure through an O-glycosidic bond.Péptido modificado o una sal farmacéuticamente aceptable del mismo, en el que el péptido modificado tiene una estructura representada por la fórmula de uno de los siguientes compuestos 2-1, 2-3, 2-10, 2-11, 2-12, 2-13, 2-14, 2- 15, 2-16, 2-25, 2-26, 2-27, 2-29, o 2-30: **(Ver fórmula)** en las que hANP es hANP(1-28) que consiste en la secuencia de aminoácidos de SEQ ID NO: 1 y está unido en el extremo N-terminal de la secuencia de aminoácidos a la estructura conectora a través de un enlace amida； AG(5) es una sustancia de azúcar representada por la siguiente fórmula **(Ver fórmula)** en la que Gxx es GlcNAc y "O/N-L" representa la unión a la estructura conectora a través de un enlace O- glucosídico； AG(7) es u
