To provide a prefabricated building which can reduce the number of components for fixing a photovoltaic power generation panel on a roof body and can be thinned to improve designability.

In a prefabricated building, a roof body is fixed on a support body, and a photovoltaic power generation panel 3 is mounted and fixed on the roof body. The roof body has a plurality of lower holding members 13 and a plurality of upper holding members 14 which hold the edge of a roof panel 15 between them. The upper holding member 14 has an insertion part 58 into which a short-length frame fixing component can be inserted in the longitudinal direction, and a panel supporting frame 4 arranged along a direction orthogonal to the upper holding member 14 is fastened and fixed from above to the frame fixing component inserted into the insertion part 58. The panel supporting frame 4 has a mounting surface part on which the photovoltaic power generation panel 3 is mounted.