A semiconductor module that can realize a substantially fixed transmission time of signals transmitted through electric wirings disposed on a board via each semiconductor device mounted on a board and can reduce reflection of high-frequency signals and a method for mounting the same is provided. A plurality of semiconductor devices are mounted on a flexible board, and a semiconductor module is formed by folding the board so that the plurality of semiconductor devices are stacked. In an input signal line electrically and mechanically connected to each of the semiconductor devices and an output signal line electrically and mechanically connected to each of the semiconductor devices which signal lines are formed on the board, the sum of a first line length of the input signal line and a second line length of the output signal line for each of the semiconductor devices is set to a substantially fixed length.