蓝章（学名：Octopus cyanea），又名土婆，为章鱼科章鱼属下的一个种。

Octopus cyanea, also known as the big blue octopus, day octopus and Cyane's octopus, is an octopus in the family Octopodidae. It occurs in both the Pacific and Indian Oceans, from Hawaii to the eastern coast of Africa.

O. cyanea grows to 16 cm in mantle length with arms to at least 80 cm.