If you're travelling by public transportation, it's a mere 2-hour ride from Tokyo by Hokuriko Shinkansen bullet train.
From Iiyama station, it's 25 minutes by bus to Nozawa Onsen village. Please visit www.navitime.co.jp for train schedule.
If you're driving, it's just under 4 hours from Tokyo on the Shinshu Expressway.
Nozawa Onsen village is easily accessible via the Shinshu Expressway.