To make a contribution to impression taking with high accuracy by correctly recognizing the compatibility of a tray within the oral cavity in the trial test or the tray in dental impression taking.

The ready-made dental impression taking tray consisting of material having characteristics of the high transparency and low refractive index is made in such a manner that the regions and states in the oral cavity can be checked through the tray. For example, transparent dental methyl methacrylate base resin, tempered glass, heat resisting glass or general plastics, etc., are usable as the tray material. More preferably, the tray material is required to be physically solid and chemically stable and to be biologically harmless to the human body in addition to the characteristics of the high transparency and the low refractive index.