The direction of photocurrents observed on two types of monolayer with different orientations of a linear triad was studied. One monolayer was deposited on a metal substrate having a hydrophilic surface; the other was deposited on one having a hydrophobic surface. The anodic photocurrent of the former monolayer was measured by the conventional photocell used in previous studies; the cathodic photocurrent of the latter was measured by a new type of photocell. These directions of photocurrents were consistent with the directions of the rectifiabilities of the monolayers which were expected from the energy diagrams of constituent moieties of the triad in the two monolayers.