The present invention provides a photobioreactor for the economical and effective mass production of a photosynthetic microorganism, comprising a culture container capable of shape maintenance, which can hold a photosynthetic microorganism to be cultured and a liquid for dispersing the photosynthetic microorganism, wherein the whole or at least a part of the culture container comprises a barrier through which water and nutrients can pass but which limits the diffusion of the photosynthetic microorganism.