A new measurement method of in-plane deformation of a diffusing object by holographic interferometry is developed. The principle of this method is based on the fringe-visibility, while the conventional method on the fringe-order. The dependence of the fringe-visibility on the pupil in the reconstructing system and the displacement of each point of the object is investigated. The visibility is determined by the auto-correlation function of the transmission function with respect to the displacement. This property can be applied to the measurement of in-plane deformation. It is proposed that multiple-slits are used as a pupil to obtain a high accuracy, with which the visibility can be rapidly varied with respect to the displacement. This method has the following advantages; 1) The desired information of the deformation can be drawn out on the reconstruction stage. 2) The sensitivity is variable and the measurable range covers from the wavelength to hundreds microns. 3) By choosing suitable pupils the displacement in the specified direction and the absolute value of it can be measured.