We propose a method for constructing "neuron-muscle fibers" driven by signals from activated neurons. The fibers consist of stretched muscle fibers covered with highly aligned neurons, and the axons of neurons extend into muscle fibers and form neuromuscular junctions (NMJs). We successfully constructed the neuron-muscle fibers by culturing neural stem cells on stretched muscle fibers; the neural stem cells then differentiated into neurons and connected to muscle cells, forming NMJs. Furthermore, we found that the neuron-muscle fibers contract after treatment of glutamic acid that activates neurons to stimulate the muscle cells. We believe that our neuron-muscle fibers will be not only used as soft-robotic actuators controlled by neuronal signals, but also used in therapeutic and pharmacokinetic assays for NMJ disease models.