Infancy trees, i.e. trees in their early stage, in neat epoxy and epoxy/silica nanocomposite were investigated in terms of their generation time and morphology. Generation time represented by V-t characteristics obeys a formula Voct-n. It is to be noted that similar effects are imposed not only on mm order long trees but also on several tens μm order short infancy trees. Infancy tree generation time is increased by nano filler 5 wt% addition and by surface treatment of nano filler. The same thing can be said to a value 'n'. As for morphology of the infancy trees, it was clarified from optical microscope observation that there is no significant difference either in epoxy or in nanocomposite, as far as their lengths are almost the same. An infancy tree seems to grow at first between neighboring nano filler particles and to extend by contacting nano filler particles in their growing path. Since the infancy tree is thin in the beginning and becomes thick afterwards, chance of the tree to meet with nano filler is considered to be increase.