A method for manufacturing a solar cell (103, 104, 105) comprising a rectangular crystalline silicon substrate, the method comprising the steps of depositing a thin-film on at least one of a first principal surface and a second principal surface of a square crystalline silicon substrate; and dividing the square crystalline silicon substrate provided with the thin-film into two rectangular crystalline silicon substrates, wherein each rectangular crystalline silicon substrate after division has a rectangular first principal surface, a rectangular second principal surface positioned on a side opposite to the first principal surface, a first lateral surface (91, 95) connecting one long side of the first principal surface and one long side of the second principal surface, and a second lateral surface (92, 92') positioned on a side opposite to the first lateral surface (91, 95) and connecting another long side of the first principal surface and another long side of the second principal surface, wherein in deposition of the thin-film, the thin-film is formed not only on the principal surface of the square crystalline silicon substrate, but also formed extended onto lateral surfaces of the square crystalline silicon substrate, thereby the first lateral surface (91, 95) of the rectangular crystalline silicon substrate after division is covered with the thin-film, and the second lateral surface (92, 92') is not covered with the thin-film, characterized in that the method further comprising heating the second lateral surface (92, 92') of the rectangular crystalline silicon substrate at a temperature of 100 to 200°C in an oxidizing atmosphere to form an oxide film on the crystalline silicon exposed on the second lateral surface (92, 92'). depositing a thin-film on at least one of a first principal surface and a second principal surface of a square crystalline silicon substrate; and dividing the square crystalline silicon substrate provided with the thin-film into two rectangular crystalline silicon substrates, wherein each rectangular crystalline silicon substrate after division has a rectangular first principal surface, a rectangular second principal surface positioned on a side opposite to the first principal surface, a first lateral surface (91, 95) connecting one long side of the first principal surface and one long side of the second principal surface, and a second lateral surface (92, 92') positioned on a side opposite to the first lateral surface (91, 95) and connecting another long side of the first principal surface and another long side of the second principal surface, wherein in deposition of the thin-film, the thin-film is formed not only on the principal surface of the square crystalline silicon substrate, but also formed extended onto lateral surfaces of the square crystalline silicon substrate, thereby the first lateral surface (91, 95) of the rectangular crystalline silicon substrate after division is covered with the thin-film, and the second lateral surface (92, 92') is not covered with the thin-film, characterized in that the method further comprising heating the second lateral surface (92, 92') of the rectangular crystalline silicon substrate at a temperature of 100 to 200°C in an oxidizing atmosphere to form an oxide film on the crystalline silicon exposed on the second lateral surface (92, 92'). wherein each rectangular crystalline silicon substrate after division has a rectangular first principal surface, a rectangular second principal surface positioned on a side opposite to the first principal surface, a first lateral surface (91, 95) connecting one long side of the first principal surface and one long side of the second principal surface, and a second lateral surface (92, 92') positioned on a side opposite to the first lateral surface (91, 95) and connecting another long side of the first principal surface and another long side of the second principal surface, wherein in deposition of the thin-film, the thin-film is formed not only on the principal surface of the square crystalline silicon substrate, but also formed extended onto lateral surfaces of the square crystalline silicon substrate, thereby the first lateral surface (91, 95) of the rectangular crystalline silicon substrate after division is covered with the thin-film, and the second lateral surface (92, 92') is not covered with the thin-film, characterized in that the method further comprising heating the second lateral surface (92, 92') of the rectangular crystalline silicon substrate at a temperature of 100 to 200°C in an oxidizing atmosphere to form an oxide film on the crystalline silicon exposed on the second lateral surface (92, 92').