Watazumi Doso (海童道祖, [わたづみ　どうそ] Error: {{nihongo}}: transliteration text not Latin script (pos 1) (help), Watazumi Dōso) Roshi (November 20, 1911 - December 14, 1992) was a master of the end-blown Japanese bamboo flute. He studied Rinzai Zen, attaining the title of rōshi.

Born as Tanaka Masaru, he was also known as Tanaka Fumon, Itcho Fumon, Watazumi Fumon, and Watazumi Shuso.

Watazumi played unlacquered instruments that he referred to as hotchiku, in contrast with the modern shakuhachi, stressing that to truly understand nature and oneself, one had to use an instrument of the most raw and natural origin. From this grew what he called Watazumidō "Way of Watazumi".

In addition to hotchiku, Watazumi used the jō for exercise, invigoration, and training.