To obtain the subject accelerator capable of increasing germination rate when spread after seeding and also of improving subsequent growth conditions by including a specific cyclodextrin as an active ingredient.

This plant growth accelerator is obtained by including a cyclodextrin which is composed of 6 to 8 glucose units and produced by subjecting 1 to 2 hydroxyl group(s) per glucose unit to chemical modification preferably through glycosylation, maltosylation, methylation or the like. The cyclodextrin has a solubility in water of preferably ≥80 g/100 ml, and is preferably used as a 1-3% aqueous solution, and it is preferable that the above aqueous solution is sprayed on sown seed surface at 100 to 1,000 ml per m2 about once a week until the resulting plant sprouts grow to around 10 cm high.