PROBLEM TO BE SOLVED: To obtain an oral agent capable of enhancing fluidity of blood and having sure ameliorating effects on blood circulation and high safety without adverse effects. SOLUTION: The agent or food comprises a plant of the genus Bidens, especially Bidens pilosa L. or an ingredient thereof and has high effectiveness. The method for ameliorating the blood circulation uses the agent. The blood circulation can be ameliorated and suppression of exacerbation of symptoms can be expected in not only patients suffering from Livedo reticularis with summer ulceration and repeating relapse but also patients suffering from various kinds of intractable hematogenous disorders simply by drinking a healthy tea as a part of eating habits or ingesting the agent. The facts should be regarded as exceedingly valuable good news.