A response mechanism of nematic liquid crystals following the switching‐on and off of an in‐plane electric field when using the in‐plane switching (IPS) mode was investigated. Simplified theoretical expressions, which were derived with an assumption that an in‐plane electric field was applied to the liquid crystals, were used to explain the dynamical switching process in the IPS mode. In particular, the relaxation time of the liquid crystals when removing the electric field was described as a proportional relationship to the square of the cell gap. A thinner cell gap also proved to be effective in obtaining a fast response time in the IPS mode. By contrast, the switching‐on time when applying the in‐plane electric field proved to be inversely proportional to the difference between the square of the electric field strength and the square of the critical electric field strength at which the liquid crystals begin to deform. ©1996 American Institute of Physics.