A planetary gear train includes an input shaft, an output gear, first to third planetary gear sets respectively having first to third, fourth to sixth, and seventh to ninth rotation elements, a first shaft fixedly connected to the second rotation element and the input shaft, a second shaft fixedly connected to the sixth and eighth rotation elements and the output gear, a third shaft fixedly connected to the first rotation element and a transmission housing, a fourth shaft fixedly connected to the third rotation element, a fifth shaft fixedly connected to the fourth and seventh rotation elements, a sixth shaft fixedly connected to the fifth rotation element, and a seventh shaft fixedly connected to the ninth rotation element.