A new grazing-incidence reflectometer has been designed for the X-ray undulator beamline BL-39XU at SPring-8. It will be used for analytical applications, especially ultra-trace-level determination by total reflection X-ray fluorescence (TXRF), nanometer-scale surface topography by specular/non-specular X-ray reflection, and thin-film interface studies by combined measurements of X-ray fluorescence and X-ray reflection. The requirements for the instrument and the solutions in the present design are discussed. A prototype has been developed to test the feasibility of the design. It has been confirmed that the measurements planned at the beamline are achievable with this reflectometer.