Derbyshire Fire and Rescue Service said the blaze involved a single-storey barn, measuring 70 metres by 20 metres, in Smalldale.
Retained fire crews from Buxton and Clay Cross were sent to the scene at around 2am.
Derbyshire police were also in attendance, the spokesperson added.
The incident was reported to be still ongoing as of 6.45am this morning. More on this when we get it.