Objective of this research is to study the presence of 3D flash lag illusion created by a moving object that has a motion-in-depth and a flash object. An object consisting of two thin sticks was simulated to approach the subject who observed it with a stereoscope. In the process of approaching, another stick was briefly presented in the middle of the moving sticks. Five human subjects took part in our experiments and all perceived 3D flash lag illusion. The perceived depth created by 3D flash lag illusion was measured by two different psychophysical experiments, by use of a vernier caliper and by a method of nulling with another depth cue. We studied relation between the perceived depth and the presentation distance. The experimental results indicate that the perceived gap by 3D flash lag illusion is independent from the presentation distance.