In the Orbital Reentry Experiment (OREX) done by Japanese for the first time, the onboard measurement mission is one of the most important purposes. Toward the R&D of the HOPE (H-IIOrbiting Plane), acquisition of the basic data during the atmospheric re-entry and the flight validation of the design methods were expected by OREX as well as flight verification of the thermal protection structures. Therefore, the various measurements aboard OREX were planned as its mission: 1) aerothermodynamical measurements as a probe or a flying wind tunnel, 2) measurements for verification of the thermo-structural design, 3) measurements on the communication blackout phenomena, 4) GPSR navigation data acquisition. Requirements and decision for the measurement items and selection of measuring apparatus for each item have been made. Design, development and test have followed. Discussed are the mission scenario, the outline of the design, development story and spatial allocation of the sensors.