Evaporative removal process of gelatin has been studied by irradiating Nd : YAG laser over an ink-mixed gelatin specimen, which is assumed to simulate an organismm. The reaction of gelatin at various temperatures was investigated using differential thermal analysis as the first step. Evaporation of water in the gelatin occurs over a wide temperature range while some minor reactions are observed additionally. The unsteady heat conduction equation in the gelatin was nondimmensionalized to result in four important dimensionless numbers. Among them, the effect of Fourier number(dimensionless irradiation time)and Biot number(surface quenching)were partly studied by measuring the shape anf size of the drilled hole by a CW multimode Nd : YAG laser. The volume of hole was almost proportional to the irradiation time while the hole shape became flat and wide with longer irradiation time. Increase of Biot number resulted in decrease of hole depth. The experimental technique used in this study can be further employed to study the effect of the relavant parameters more in depth.