To provide a structure for mounting a photovoltaic panel to a roof part of a building in which there is no risk of reducing a strength of a fixing member or impairing appearance since it is not necessary to perform excessive hole opening processing on the fixing member even in a photovoltaic panel of which the panel size is different in accordance with a manufacturer difference, and it is not necessary to have many kinds of members in stock for each panel size.

A mounting crosspiece 1 extends in a direction (a) orthogonal with one side 31 of a photovoltaic panel 3 formed from polygons, and a fixing member 2 extends in a direction along the one side 31 of the photovoltaic panel 3. The fixing member 2 is mounted through a mounting part 11 which is formed along an extending direction of the mounting crosspiece 1, to the mounting crosspiece 1 so as to be movable in the direction orthogonal with the one side 31 of the photovoltaic panel 3.