Spain's Civil Guard arrested Ignacio G.H on the weekend on suspicion of having started the fire in Majorca.
He spent Monday night in police custody and was expected to appear before a judge as early as Tuesday.
Two other men have also been charged for starting the forest fire.
Ignacio G.H is the brother of Samuul G.H, in charge of the farmstead where the fire originated.
Samuel was earlier arrested but then freed on bail while authorities continued to investigate the cause of the fire.
Those investigations ended with the arrest of his brother, aged 44, and of two friends, Spain's El Mundo newspaper reported on Tuesday.
Investigators believe the three men were enjoying a barbecue on Thursday at Samuel's farm.
Ignacio and his two friends had then thrown the hot coals over a ploughed field.
This became the fire that destroyed almost 1,800 hectares of the World Heritage Tramuntana mountains, police believe.
No one was injured in the fires, although one fireman was treated for dehydration.