Three innovation diffusion models of technology (KKKI-KKKIII) are proposed. The first two of these models are motivated by Smith's model and von Bertalanffy's model already in use in population dynamics. The first model also takes into account the internal and external influences of imitators and innovators. The third model is an improvement over models by Floyd and Fisher-Pry. It can also be looked upon as a model which takes into account the effect of promotional subsidies on the innovation diffusion. Empirical analyses using the data of three technological innovations show that the proposed models give comparable or better results.