Ajbelj (; in older sources also Ajbel; , also Eibel or Eibl) is a settlement in the Municipality of Kostel in southern Slovenia. The area is part of the traditional region of Lower Carniola and is now included in the Southeast Slovenia Statistical Region. It is a linear village standing on a hill above Kaptol. To the southeast is a karst polje with sinkholes where there are tilled fields, hay fields, and wooded land. There are large numbers of wild boar, bears, deer, foxes, and badgers in the area.