In pulse-power technology, a transformer-type accelerator is a good candidate for a highvoltage pulse generator suitable for repetitive operations. In this article, a reverse-conducting thyristor has been used as a switching element in a primary circuit and good operations have been obtained. A dual-resonant mode and the mode proposed by Reed, preferable to the former in the sense of voltage gain, have been investigated experimentally. A voltage gain of 25% increase compared to that of the dual-resonant mode operation has been obtained. Two different types of transformers, a spiral and a Tesla type with various turn ratios, were constructed and the characteristics of each type when applied to the same circuit have also been investigated in detail. As a result, it has been made clear that the stray capacitance of the secondary winding restricts the upper limit of the turn ratio to get the large voltage multiplication.