The fish market is a three minute walk from Tsukiji Station. Leaving the station take Exit 2, walk straight, then cross the main road. Continue straight, before crossing a second road. The Tsukiji Outer Market will be on your left hand side.
From Shinjuku Station to Tsukiji Station:
Take the Marunouchi Line to Ginza Station, then take the Hibiya Line to Tsukiji Station (19 minutes, ¥200)From Tokyo Station to Tsukiji Station:
Take the Yamanote Line to Yurakucho Station, walk three minutes to Hibiya Station then take the Hibiya Line to Tsukiji Station (12 minutes, ¥310)