Sigma operates two wind farms, the 16MW Shin-Kamigoto Whales wind farm in Nagasaki prefecture and the 2MW Nagashima-Kuronose plant in Kagoshima prefecture
The company is also set to build a new farm in Shin-Nagashima in Kagoshima, which is scheduled to start operation in 2014.
On top of this, there are plans at various stages of development for four more wind farms in Tohoku, Chugoku and Shikoku regions of Japan.
Toshiba previously moved to establish a footprint in the wind market when in 2011 when it invested $36 million in South Korean turbine manufacturer Unison.
It is also a member of a consortium looking to establish floating offshore wind projects in Japanese waters.
Toshiba has historically been one of the big players in Japan's nuclear industry, but as the country moves away from nuclear generation the firm is looking to establish new revenue streams.
The company will also be keen to portray a greener face following the partial meltdown of Toshiba reactors at the Fukushima nuclear power plant.
Following completion of the deal, expected in November, Sigma will be fully owned by Toshiba.