In thermal ink jet (TIJ) printhead design, in order to satisfy various market demands, it is important to consider how effectively the printhead transfers input energy to ejected drop performance. First, we defined energy efficiency as a ratio of ejected ink drop energy (the sum of kinetic and surface energy) to consuming electric energy in the heater of thermal ink jet printhead. We examined a method for increasing the energy efficiency in terms of printhead design, and we found that it relates with an inertance ratio of the rear fluid pass to the front. We proposed a new side shooter thermal ink jet printhead for improvement of the inertance ratio, and we tried to fabricate channels on silicon wafers by a reactive ion etching (RIE). The printhead achieved higher energy efficiency when compared with the conventional design and it has been proved that high energy efficiency enables low consuming energy or high drop energy, and other good characteristics have been also obtained by the printhead.