Background and Objectives: Overweight and obesity increase the risk of hypertension, type 2 diabetes, and other metabolic disorders and are increasing in Japan, particularly among men. Several prospective studies have suggested that high vegetable intake is inversely associated with weight gain. Here, the association between vegetable consumption and weight gain in a group of food manufacturing workers over the course of one year was investigated. Methods and Study Design: The study was a one-year cohort study of the nutrition and lifestyle survey. The study population consisted of 900 and 910 Japanese employees (aged 19-60 years) from a manufacturing company located in Musashino City, Tokyo, Japan, that were administered the same validated brief selfadministered diet history and dietary lifestyle questionnaire in 2006 and 2007, respectively. Clinical examinations of body weight were also performed to assess changes in weight. We analyzed participants who responded in both 2006 and 2007 (n=478). Results: Risk of weight gain of more than 3 kg was significantly lower in the group consuming the most vegetables than in the group consuming the least, and this difference remained significant after adjustment for baseline age, sex, and consumption of other foods (p for trend=0.028). Conclusions: Weight gain was inversely associated with high consumption of vegetables. Encouraging Japanese employees to consume more vegetables may be an important strategy in controlling weight gain and preventing metabolic syndrome.