Abstract: A weight training auxiliary device for adjusting a weight training load of training equipment includes a plurality of weights that generate a load, a load transmission mechanism configured to transmit the load of the weights to the training equipment, and a weight attaching/detaching mechanism configured to attach and detach the weights. At least one of the weights has an electromagnet or a permanent electromagnet built in. The weight attaching/detaching mechanism includes a conduction relay configured to control supply of power to the electromagnet or the permanent electromagnet so that the weight training load is adjusted by attaching or detaching the at least one of the weights.