One aspect of the present invention is a solar cell substrate, comprising: a lower substrate; and a lower electrode that is formed on the upper part of said lower substrate, wherein a metal diffusion-preventing film having at least one or two or more metal layers is included between said lower substrate and said lower electrode, and if two or more metal layers are formed, the metal layers adjoining each other can be different metals. Additionally, a solar cell, which is another aspect of the present invention, comprises: a lower substrate; and a lower electrode that is formed on the upper part of said lower substrate, wherein a metal diffusion-preventing film having at least one or two or more metal layers is included between said lower substrate and said lower electrode, and if two or more metal layers are formed, the metal layers adjoining each other comprise solar cell substrates which are of different metals; p-type light absorption layers formed on said solar cell substrates; n-type buffer layers formed on said light absorption layers; transparent windows formed on said buffer layers; and upper electrodes formed on said transparent windows.