A hot-water supply unit, comprising: a heating mechanism configured to heat up heating medium; a tank configured to store water heated up by the heating medium; at least one water pipe connected with the tank, and configured to be a part of a water circuit for supplying water from the tank to a hot-water destination; thermal insulator adhering to and substantially surrounding the tank; a main frame supporting the heating mechanism and the at least one water pipe to be at a position above the tank and the thermal insulator; a support plate (500, 900) disposed between the thermal insulator and the main frame; and a housing accommodating the heating mechanism, the tank, the at least one water pipe, the thermal insulator, the main frame and the support plate, wherein: the thermal insulator connects the tank and the support plate; the main frame is fixed to the support plate to be supported by the support plate; and a top part of the tank has a convex shape, characterized in that: the thermal insulator adheres to the tank at at least the top part of the tank, and adheres to the support plate at at least a bottom surface of the support plate directly above an area where the thermal insulator adheres to the top part of the tank; both the insulator and the support plate have a convex shape part along the top part of the tank; and the support plate is a drain member configured to receive water. a heating mechanism configured to heat up heating medium; a tank configured to store water heated up by the heating medium; at least one water pipe connected with the tank, and configured to be a part of a water circuit for supplying water from the tank to a hot-water destination; thermal insulator adhering to and substantially surrounding the tank; a main frame supporting the heating mechanism and the at least one water pipe to be at a position above the tank and the thermal insulator; a support plate (500, 900) disposed between the thermal insulator and the main frame; and a housing accommodating the heating mechanism, the tank, the at least one water pipe, the thermal insulator, the main frame and the support plate, wherein: the thermal insulator connects the tank and the support plate; the main frame is fixed to the support plate to be supported by the support plate; and a top part of the tank has a convex shape, characterized in that: the thermal insulator adheres to the tank at at least the top part of the tank, and adheres to the support plate at at least a bottom surface of the support plate directly above an area where the thermal insulator adheres to the top part of the tank; both the insulator and the support plate have a convex shape part along the top part of the tank; and the support plate is a drain member configured to receive water. the thermal insulator connects the tank and the support plate; the main frame is fixed to the support plate to be supported by the support plate; and a top part of the tank has a convex shape, characterized in that: the thermal insulator adheres to the tank at at least the top part of the tank, and adheres to the support plate at at least a bottom surface of the support plate directly above an area where the thermal insulator adheres to the top part of the tank; both the insulator and the support plate have a convex shape part along the top part of the tank; and the support plate is a drain member configured to receive water. the thermal insulator adheres to the tank at at least the top part of the tank, and adheres to the support plate at at least a bottom surface of the support plate directly above an area where the thermal insulator adheres to the top part of the tank; both the insulator and the support plate have a convex shape part along the top part of the tank; and the support plate is a drain member configured to receive water.