A planetary gear train of an automatic transmission may include input and output shafts, first to fifth planetary gear sets respectively having first to third, fourth to sixth, seventh to ninth, tenth to twelfth, and thirteenth to fifteenth elements, a first shaft fixed with the first and fifth elements and the input shaft, a second shaft fixed with the fourteenth element and the output shaft, a third shaft fixed with the third and fourth elements, a fourth shaft fixed with the sixth and tenth elements, a fifth shaft fixed with the eighth, eleventh, and fifteenth elements, a sixth shaft fixed with the ninth element, and a plurality of shafts, each of which is selectively connectable to a housing and fixed to an element of the first, third, fourth, and fifth gear sets which is not fixed with the first to sixth shafts.