Provided is a sliding door device of a nacelle for a wind turbine. The sliding door device of a nacelle for a wind turbine comprises: a sliding door which slides in a first direction to be opened, wherein the sliding door is located on a first height equal to the height of an upper surface of the nacelle in a closing location; a U-roller which enables the sliding door to slide by rotation while the U-roller is connected to the sliding door; a lower guide rail for guiding a moving path of the U-roller under the U-roller; and an opening and closing device for pushing the U-roller in the first direction or pulling the U-roller in the direction opposite to the first direction. The lower guide rail has a slope which gets higher in the first direction. The lower guide rail is located on a second height to be opened when the sliding door is opened.
