In 1953, Iwao Yasuda reported on the piezoelectricity of bone and the electrical stimulation of callus formation. Subsequently, various methods of electrical stimulation have been investigated, and the enhancement of callus formation by electrical stimulation is likely to have broad clinical applications for not only the repair of fractures, but also for nonunion and pseudoarthrosis. Recently, these outcomes have been validated by significant double blind clinical trials, and the electrical currents in bone were investigated at the molecular level. Moreover, the application of impedance measurements obtained upon electrical stimulation as a means to evaluate bone maturation was examined. This paper reports on the current methods of electrical stimulation, the fundamental effects on bone formation, and further clinical applications.