The NPA based diagnostic complex in ITER consists of four diagnostics: the neutral particle analyzers, the diamond neutral particle spectrometer, the gamma-ray spectrometer, and the neutron spectrometer. The diagnostics are located in equatorial port #11 and share the same vacuum channel. The present paper considers the physical basis of the diagnostic complex and its measurement capabilities in ITER. In addition, the design of the complex and the engineering solutions implemented to meet the ITER requirements are described.