The present invention aims to provide a method for improving the fluidity of a crystal nucleating agent for polyolefin resins without impairing other properties, and a polyolefin resin composition containing the crystal nucleating agent with improved fluidity and having excellent properties including transparency, and a molded article thereof. A crystal nucleating agent controlled to have specific characteristics can achieve improved fluidity, and the use of such a crystal nucleating agent having specific characteristics remarkably improves the workability during molding processing and provides a polyolefin resin composition excellent in properties such as transparency, and a molded article thereof.