To provide a construction method on a roof that can lay roof tiles efficiently by forming a roof tile assembly with the roof tiles arranged in a line.

In the construction method of a snow melting device, a sheet like heating body 3 is laid between a sheathing roof board 1 and roof tiles 5 of a house to build up a device for heating the roof tiles 5. In this case, the adjacent side parts of a plurality of roof tiles 5 are pressure-connected to each other by pressing means 8, 9 so as to form a roof tile assembly 5A with a plurality of roof tiles 5 arranged in a line. After laying the plane heating body 3 at the back face of the roof tile assembly 5A or on the sheathing roof board 1, the roof tile assembly 5A is laid on the sheathing roof board 1, and the pressing means 8, 9 are eliminated to lay the roof tiles in specified positions.