Novel, safe, and highly effective agents for increasing adiponectin in blood that contain astaxanthin and/or an ester thereof as an active component are provided. Due to an increase in the amount of adiponectin in blood, the action of adipocytokine such as TNF.alpha. can be decreased, or the action of biologically active substances such as insulin can be protected from the adverse action of adipocytokine. It is expected that, as a result, insulin resistance and hyperinsulinemia caused by adipocytokine, and metabolic syndrome are prevented or suppressed. Furthermore, it is expected that progress of arteriosclerosis, which can lead to cardiovascular diseases and cerebrovascular diseases, is inhibited by ingestion of the agent for increasing adiponectin in blood of the present invention, because arteriosclerosis progresses due to a decrease in adiponectin.