[en] A new tuning method of the gap voltage distribution has been developed for an interdigital H type linac. With an asymmetrically ridged IH resonator, the voltage distribution was significantly improved by introducing a pair of Wing Tuners. The quality factor and the shunt impedance of the resonant cavity remained practically unchanged by these inductive tuning elements. The Wing Tuners strongly affect on linac characteristics similarly to the local reduction of the resonator diameter. A prototype IH linac has been constructed to demonstrate the operational capabilities of the tuning method. The linac is designed to accelerate protons from an energy of 15 to 161 keV with an rf frequency of 100 MHz. The linac tank is made of mild steel, and 48 and 92 cm in diameter and in length, respectively. The drift tube structure of π/3π mode is adopted, and an electrostatic quadrupole lens is installed in every 3π drift tube. The experimental results of the proton model agree well with the design characteristics. (author)