To provide a method for converting dried laver seaweed, belonging to the genus Porphyra into single cell forms based on a new cell-stimulating method.

This method for converting the dried laver seaweed into the single cell forms is provided, by performing an acid treatment or alkaline treatment in combination with the culture of thallus of the dried laver seaweed belonging to the genus Porphyra under maturing condition to accelerate the degradation of the thallus and also making it positively release single cells, such as monospores and carpospores. As a result, (1) it is possible to utilize the monospores for the culture of the laver by releasing them advantageously; (2) by using the monospores, it becomes possible to stably supply/grow species equipped with superior characteristics as a cloning technology; and (3) it also becomes possible to utilize various kinds of single cells isolated from the thallus as a feed used for culturing fishes and shellfishes.