Disclosed is a cell mass containing an adipose-tissue-derived multipotent progenitor cell. Also disclosed is a method for producing an adipose-tissue-derived multipotent progenitor cell from an adipose tissue, which comprises the steps of: (a) removing erythrocytes from an adipose-tissue-derived cell mass to produce a preadipose-tissue-derived multipotent progenitor cell mass; and (b) removing cells other than the adipose-tissue-derived multipotent progenitor cell from the preadipose-tissue-derived multipotent progenitor cell mass to produce the desired adipose-tissue-derived multipotent progenitor cell. Further disclosed is an adipose-tissue-derived multipotent progenitor cell produced by the method.