The invention provides a plastic impression tray for an upper jaw having a bottom portion provided with an outer wall and a bulge portion. A rim is provided along an upper end of the outer wall, elongated through holes having a particular width are provided in the outer wall such that a distance between the adjacent through holes is particular times the width, similar elongated through holes are provided in the bulge portion, circular through holes having a particular diameter are provided at the center of the distances of the adjacent elongated through holes in the outer wall, and elongated end portion side through holes having particular width and length are provided on a line connecting the bottom portion side end portions of the elongated through holes at the closest side to the end portions of the U-like shaped portion in the outer wall and the bulge portion.
