There has not been an electric-magnetic flux leakage (MFL) detector enabling nondestructively testing the in-service mine hoist wire ropes fixed at both ends mainly due to the tubular configuration of solenoids as electric magnetizers. Hence, an opening electric magnetizer is proposed based on the magnetic control for a C-like electric loop-coil, featured by an opening structure capable of directly encompassing and centering the endless object in it. Subsequently, the magnetization effect similar to the conventional solenoids is confirmed by simulations and experiments with the designed 3-D models and prototypes. Finally, an opening electric-MFL detector chiefly consisting of the opening electric magnetizer is presented, capable of directly encircling the endless ropes, and meanwhile two application cases of the relevant apparatuses for the in-service mine hoist wire ropes are given with a good detection effect. The emergence of the opening electric magnetizer and its detector can expand the application ranges beyond of the traditional tubular solenoids and their corresponding tubular sensors, including other electromagnetic excitation or nondestructive testing for the endless objects, such as railway and coiled tubing in service.