To provide a corner structure of a balcony capable of improving the connection strength, stability, waterproofness of mutual walls, and workability.

The corner structure of a balcony formed by jointing a plurality of lightweight concrete wall panels (10, 20, 30 ) is fixed onto a first wall panel 10, a second wall panel 20 jointed in an outside corner relation with the first wall panel 10, a third wall panel 30 fixed onto the first wall panel 10, and a fourth wall panel 40 connected onto the second wall panel 20 in an outside corner relation. The fourth wall panel 40 is formed thicker than the second wall panel 20. The end face 32 at which the third wall panel 30 is connected to the fourth wall panel 40 is positioned in a place separated from the inside face of the second wall panel 20.