The present invention provides a method for manufacturing a multi-junction solar cell which makes it possible to implement a 4-junction solar cell and to increase the area of a device. A nucleus generation site is disposed on a substrate 2 made of a first semiconductor. A first material gas is fed to the nucleus generation site to form a wire-like semiconductor 3 in the nucleus generation site. A third material gas and a fourth material gas are fed to form a wire-like semiconductor 4 on the semiconductor 3 and a wire-like semiconductor 5 on the semiconductor 4. A nucleus generation site is disposed on a substrate 6. The first material gas is fed to the nucleus generation site to form a wire-like semiconductor 2a in the nucleus generation site. A second material gas to the fourth material gas are fed to form the wire-like semiconductor 3 on the semiconductor 2a, the wire-like semiconductor 4 on the semiconductor 3, and the wire-like semiconductor 5 on the semiconductor 4. The bandgaps of the semiconductors decrease and increase consistently with the distance to the substrate 2 or 6. The nucleus generation site is made of catalytic particles such as Au. The semiconductors 2 and 2a are Ge, the semiconductor 3 is InxGa1-xAs, the semiconductor 4 is GaAs, and the semiconductor 5 is AlyGa1-yAs.