The Lactobacillus being attached which is the lactobacillus, prevention of the endometriosis which contains especially Lactobacillus gasseri OLL2809 stocks and/or the improvement medicine is offered. In addition, prevention of the endometriosis which includes the particular lactobacillus and/or prevention of the endometriosis which features the eating and drinking item constituent for improvement and that the particular lactobacillus is prescribed and/or improvement manner is offered.乳酸菌であるLactobacillus属、特にLactobacillus gasseri OLL2809株を含有する子宮内膜症の予防及び/又は改善剤を提供する。また、当該乳酸菌を含む子宮内膜症の予防及び/又は改善用の飲食品組成物及び当該乳酸菌を投与することを特徴とする子宮内膜症の予防及び/又は改善方法を提供する。
