Transport from Nagano station to Jigokudani

I will be staying at Hotel Metropolitan Nagano (travelling from Haneda International airport) and planning to Jigokudani. Need advice on the transport which is best in term of timing (shortest walking distance from the station to the park) and fare.

Thank You.

What time of the year?

Outside of winter, it is best to rent a car and access the park from the closest parking lot that does not enjoy access by public transportation. However, in winter, this parking lot is not accessible by car.

The next best is to take the direct bus from Nagano Station to the "Snow Monkey Park" bus stop:
http://www.japan-guide.com/e/e6028.html#/section_getThere

Here is the summer timetable for 2016:
http://www.nagadenbus.co.jp/robus/2016natsu/kyuko_s.htm

Thank Uji. I am planning to go there 15 June 2016. I will arrive at Nagano around 12:00. Do you think it is still make sense to go there? it is interesting to see the monkey during summer time?