A solar-power generating apparatus to be installed on the roof of a building, which is suitable for generating solar power, said solar-power generating apparatus having an upper support member (26, 28; 212, 214) and a lower support member (27, 29; 213, 215) both to be secured on the roof, and a plurality of photovoltaic modules each of which is fitted in the upper support member (26, 28; 212, 214) and the lower support member (27, 29; 213, 215); said plurality of photovoltaic modules respectively comprising a module body having a rectangular shape and a frame attached to the sides of the module body, wherein said frame is composed of an upper bar, a lower bar and a pair of side bars (65, 66); the solar-power generating apparatus characterized in that: said upper support member (26, 28; 212, 214) includes an upper groove-wall (41a, 51a) and a lower groove-wall (41b, 51b) both of which define a down-open groove (41, 51; 216) that opens downward and slantwise and has a height smaller than a thickness (h) of the photovoltaic module, a width of the upper groove-wall (41a, 51a) being smaller than a width of the lower groove-wall (41 b, 51 b); said lower support member (27, 29; 213, 215) includes an upper groove-wall (45a, 52a) and a lower groove-wall (45b, 52b), both of which define an up-open groove (45, 52; 217) that opens upward and slantwise and has a height smaller than a thickness (h) of the photovoltaic module, a width of the upper groove-wall (45a, 52a) being smaller than a width of the lower groove-wall (45b, 52b), and said lower support member (27, 29; 213, 215) being arranged below the upper support member (26, 28; 212, 214) and extending parallel to the upper support member (26, 28; 212, 214); a depth of the down-open groove (41, 51; 216) is deeper than a depth of the up-open groove (45, 52; 217); the upper bar has an insertion projection protruding integrally from a middle part in a thickness direction of the upper bar, said insertion projection being a thin flat plate that is thinner than the upper bar and extending in a lengthwise direction of the upper bar; the lower bar has an insertion projection protruding integrally from a middle part in a thickness direction of the lower bar, said insertion projection being a thin flat plate that is thinner than the lower bar, extending along the lower bar and having a width that is smaller than a width of the insertion projection; and by inserting the insertion projection of the lower bar of the frame of the photovoltaic module into the up-open groove (45, 52; 217) of the lower support member (27, 29; 213, 215) after an insertion of the insertion projection of the upper bar of the frame into the down-open groove (41, 51; 216) of the upper support member (26, 28; 212, 214), the insertion projection of the upper bar of the frame of the photovoltaic module catches and holds the upper groove-wall (41a, 51a) of the down-open groove (41, 51; 216) of the upper support member (26, 28; 212, 214), and the insertion projection of the lower bar of the frame of the photovoltaic module contacts and is held by the upper groove-wall (45a, 52a) of the up-open groove (45, 52; 217) of the lower support member (27, 29; 213, 215). said upper support member (26, 28; 212, 214) includes an upper groove-wall (41a, 51a) and a lower groove-wall (41b, 51b) both of which define a down-open groove (41, 51; 216) that opens downward and slantwise and has a height smaller than a thickness (h) of the photovoltaic module, a width of the upper groove-wall (41a, 51a) being smaller than a width of the lower groove-wall (41 b, 51 b); said lower support member (27, 29; 213, 215) includes an upper groove-wall (45a, 52a) and a lower groove-wall (45b, 52b), both of which define an up-open groove (45, 52; 217) that opens upward and slantwise and has a height smaller than a thickness (h) of the photovoltaic module, a width of the upper groove-wall (45a, 52a) being smaller than a width of the lower groove-wall (45b, 52b), and said lower support member (27, 29; 213, 215) being arranged below the upper support member (26, 28; 212, 214) and extending parallel to the upper support member (26, 28; 212, 214); a depth of the down-open groove (41, 51; 216) is deeper than a depth of the up-open groove (45, 52; 217); the upper bar has an insertion projection protruding integrally from a middle part in a thickness direction of the upper bar, said insertion projection being a thin flat plate that is thinner than the upper bar and extending in a lengthwise direction of the upper bar; the lower bar has an insertion projection protruding integrally from a middle part in a thickness direction of the lower bar, said insertion projection being a thin flat plate that is thinner than the lower bar, extending along the lower bar and having a width that is smaller than a width of the insertion projection; and by inserting the insertion projection of the lower bar of the frame of the photovoltaic module into the up-open groove (45, 52; 217) of the lower support member (27, 29; 213, 215) after an insertion of the insertion projection of the upper bar of the frame into the down-open groove (41, 51; 216) of the upper support member (26, 28; 212, 214), the insertion projection of the upper bar of the frame of the photovoltaic module catches and holds the upper groove-wall (41a, 51a) of the down-open groove (41, 51; 216) of the upper support member (26, 28; 212, 214), and the insertion projection of the lower bar of the frame of the photovoltaic module contacts and is held by the upper groove-wall (45a, 52a) of the up-open groove (45, 52; 217) of the lower support member (27, 29; 213, 215).