Saccharina japonica (Dashi kombu) is a marine species of Phaeophyceae (brown algae), a type of kelp or seaweed, that is extensively cultivated in China, Japan and Korea.

A commercially important species, Saccharina japonica is known as kombu (in China haidai, in Korea dasima), an important food from Japan. Large harvests are produced by rope cultivation, a simple method of growing seaweeds by attaching them to floating ropes in the ocean.