A millimeter wave three dimensional holographic scan imaging apparatus and a method for inspecting a human body or an article are disclosed. The apparatus comprises a first millimeter wave transceiver module, a second millimeter wave transceiver module, a first guide rail device to which the first millimeter wave transceiver module is connected in slidable form, a second guide rail device to which the second millimeter wave transceiver module is connected in slidable form, a driver configured to drive the first/second millimeter wave transceiver module to move along the first/second guide rail device, and a constrainer configured to constrain kinematic relation between the first and the second millimeter wave transceiver modules such that they only move in directions opposed to each other. They may increase scan speeds, improve scan stability, reduce scan operations and enhance the reliability of the apparatus.