Ventrosa is a village and municipality in the province and autonomous community of La Rioja, in northern Spain. It is located in the mountainous western part of the region, within the comarca of the Sierra de la Demanda.
The municipality covers an area of 72.93 square kilometres (28.16 square miles). As of 2011, it had a population of 68 people, making it one of the smallest and most sparsely populated municipalities in La Rioja.