Nowadays, there are few high level metrological devices able to measure accurately the regular reflectance in the infrared region. The Laboratoire national de métrologie et d’essais (LNE) has developed an apparatus designed for the absolute measurement of this parameter in the infrared using the goniometer technique. This method is well appropriate for the measurement of spectral regular reflectance of materials with flat, non-scattering and high reflectivity surfaces such as mirrors. The apparatus works in a wide part of the infrared region (from 1 µm to 16 µm) and can operate in the visible and near infrared spectrum too. Mirror alignments, detection system and concentricity of opto-mechanics elements were optimized to reach uncertainties going from 0,001 to 0,015 depending on the wavelengths.