The electrical characteristics of stearic acid Langmuir-Blodgett (LB) films for an in-plane were investigated to develop a gas sensor using LB films. We obtained the optimum condition for a film deposition through pi-A isotherm, and the surface pressure for the deposition as an ultra-thin film was 25 dyne/cm. The thickness of the electrode was estimated at about 1000 Angstrom by current-voltage (I-V) characteristics for an in-plane because the current was saturated at 35 layers. The current-time (I-t) and I-V characteristics were measured to investigate the response properties of organic gases. Furthermore, we could distinguished the difference of current density-voltage (J-V) characteristics for the organic gases, respectively. Also, we observed the change of conductivity as increasing the number of layers. We considered that it resulted from the difference of electronic affinity and the conduction mechanism.