In this study we attempted to suppress chatter vibration in end-milling of austenitic stainless steels with an end-mill having different helix angles. We showed there were two types of chatter vibration in end-milling with a conventional end-mill with regular helix angle. The two types of chatter vibration depend on the cutting speed. We detected these two types of chatter vibration by the developed monitoring method using laser Doppler vibrometers. We classified the two types of chatter vibration according to chatter generating tendency, frequency and vibration mode. We showed that chatter vibration generated at lower cutting speeds was regenerative chatter vibration. On the other hand, chatter vibration generated at higher cutting speeds was another type. We showed that a end-mill with different helix angles could prevent generative chatter vibration at lower cutting speeds and was also effective in suppressing chatter vibration at higher cutting speeds.