Volatile sulfur compounds (VSCs) from oral plaque are known to be an important factor for oral malodor. There are a number of deodorizing agents for halitosis in the market, and studies have shown that polyphenols have an effect on reducing oral malodor. We previously reported on the bacteriostatic and deodorizing effects against Porphyromonas gingivalis, and deodorizing effect against mercaptoethanol in vitro by using Pancil PS-SP®, which is a compound of persimmon tannin and trehalose. In this study, we evaluated the suppression of clinical oral malodor with Pancil PS-M® (abbreviated as Pancil), which is an ultrafiltrated and purified form of Pancil PS-SP® with trehalose added. Oral malodor obtained from 100 participants was determined by an MS-Halimeter®. The subjects were evaluated at one hour after waking up (control), then after swallowing the distilled water. Pancil solution was applied in the mouth and was swallowed, then oral malodor was reevaluated two minutes and ten minutes later. As a result, the level of oral malodor was significantly reduced at both two minutes and ten minutes after swallowing Pancil solution compared with the control (p<0.05). It was clearly shown that Pancil strongly suppresses VSCs in vivo.