PROBLEM TO BE SOLVED: To provide an asparagus seedling promotive in growth and excellent against environmental stress.SOLUTION: There are provided a root endophyte capable of promoting growth of the asparagus seedling and a production method of the asparagus seedling, utilizing the endophyte, wherein, the asparagus seedling promotive in the growth and excellent in environmental stress resistance is provided by raising the asparagus seedling on the culture soil mixed with a strain FERM AP-22158 belonging to Phialocephala fortinii.