We constructed a molecular optical switch, which controls the photocurrent direction using a polymer nanosheet assembly. Two polymer nanosheet photodiodes composed of ruthenium complex (sensitizer) and ferrocene (donor) polymer nanosheet pair and anthracene (sensitizer) and dinitrobenzene (acceptor) polymer nanosheet pair, respectively, were assembled on the ITO electrode. Selective excitation of ruthenium by 450 nm generated cathodic photocurrent, whereas excitation of anthracene at 389 nm generated anodic photocurrent. The results indicate that the current flow direction in the assembled film can be controlled by the irradiation wavelength.