Schottky-type cells with a photoconductive layer made of merocyanine dye Langmuir-Blodgett (LB) film were fabricated to investigate transient photocurrent properties of LB films. The laser pulse-induced transient photocurrent was deduced by differentiating the quasi-open-circuit voltage signal for security of the time resolution. The observed photocurrent showed a long time tail following an extremely rapid initial rise. The long time tail can be represented by a power-law dependence, which is regarded as evidence for dispersive conduction. The power-law decay seems to be reflecting a process limited to the interface between hydrophilic groups, where dye chromophores are located, since the properties are almost immune to change in the layer thickness.