Disclosed is a magnetic-controlled generator with built-in controller that has integrated design of power generator with magnetic resistance and control circuit unit. The built-in control circuit unit is electrically connected to an armature core, an external digital operator, and a magnetic coil, in order to convert AC power produced by the armature core into DC power to supply for the magnetic coil and meanwhile control the resistance of a flywheel by inserting a number of torque value to the external digital operator. In addition, a software is built inside the generator for instant torque calibration without connecting to extra devices. In application to training machines, the device is easy to be installed and operated without restrictions in extra spaces for a controller and configuration of wires.