To provide a power generation device using fuel cells, and capable of providing sufficient output power while effectively using the space for installing the cells.

This power generation device comprises: an installation panel 3 composed by arranging the respective cells 1 with predetermined spaces S in the surface direction; and a boosting circuit 6 for raising the output voltage of a series circuit 2 of the cells 1. Each cell 1 includes a solid electrolyte 10 sandwiched between a positive electrode 7 for reducing oxygen and a negative electrode 9 for oxidizing a fuel. The positive electrode 7 and the negative electrode 9 of each cell 1 are aligned on the same surface. The entire cell installation area excluding the predetermined spaces S from a permissible region P of the cells 1 in the installation panel 3 is occupied by the electrodes of the cells 1. Conversion efficiency η of the boosting circuit 6 satisfies η≥Wb(n)/Wa(m), where n is a number obtained by dividing the necessary voltage of an external load 5 by the cell voltage of the cells 1; Wb is output power of the n cells 1; m is a number smaller than n and not smaller than the minimum number of cells necessary for operating the boosting circuit 6; and Wa is output power of the m cells.