Two non-involute helical gears that have an involute-cycloid composite tooth profile and a modified cycloid tooth profile were designed and made to obtain high performance. Using these non-involute helical gears, the circumferential vibration acceleration of the helical gears, the tooth root stress, and the transmission error were measured on running tests. The experimental results showed that the vibration characteristics of the non-involute helical gears do not differ from those of the involute helical gear. Furthermore, we proved from pitting test results that the surface durability of the non-involute helical gears is superior to that of the involute helical gear.