A nondestructive and simple technique for determining the three-dimensional shape of fixed ink dots was developed, and the optimum conditions of laser excitation and filters to detect fluorescence were determined for both dye and pigment inks for ink jet. Most magenta and black dye inks emit fluorescence at around 580 and 667 nm through laser excitations at 543 and 633 nm, respectively. Yellow dye and pigment inks and a magenta pigment ink were also detected under this condition. The cyan dye ink was excited by 405 nm laser radiation, and the fluorescence was observed by bandpass filtering ranging from 510 to 650 nm discriminately from the paper with no fluorescent brightening agent. Cyan and black pigment inks did not emit detectable fluorescence. Fluorescence emitted from the ink jet inks by laser excitation successfully provided three-dimensional ink distributions with the optical slicing function of a confocal laser scanning microscope.