The first experimental results of the induction acceleration of a single rf bunch in the KEK proton synchrotron (KEK-PS) as well as a description of the induction accelerating system were discussed. It was found that the key devices that were required to realize an induction synchrotron were an induction accelerating cavity and a pulse modulator driving the cavity. The core material of the induction cavity that was used for the first accelerating experiment was a nanocrystalline alloy called Finemet. The results show that the charged particles, for the first time, in a high-energy accelerator ring, were accelerated with an induction accelerating system. The induction system worked well through the entire operating period without any trouble.