This paper reports a newly developed simulator for operation skill training in Double-Front Construction Machinery (DFCM) that allows novices to virtually experience tough operations repeatedly using DFCM under various conditions, including dangerous congestion. First, we selected several situations targeted where the DFCM needs to be used to provide a high level of operation skills: sorted dismantling for recycling and reusing resources, rescue and recovery work in disaster areas, and building construction. In addition, we developed an operation skill-training simulator that enables novice operators to repeatedly train with the high level of operation skills needed to easily and safely handle the DFCM in even more complicated works. This simulator system has two joysticks (set in front of a monitor) to dependency control the two fronts of the animated DFCM on the monitor. Several modes involving basic construction tasks are provided and the effects of improvement in operability achieved by the training simulator can be verified. Evaluation experiments indicated that repeated training using the simulator successfully decreased the operation time to complete a task and enhanced positioning accuracy in cooperative transportation with the two fronts. The results confirm the effectiveness of the developed simulator.