A purpose is to provide a solid electrolyte battery including a low-resistance solid electrolyte layer, a vehicle mounting this solid electrolyte battery, a battery-mounting device, and a manufacturing method of the solid electrolyte battery. A solid electrolyte battery 1 includes a positive active material layer 21 containing positive active material particles 22, a negative active material layer 31 containing negative active material particles 32, and a solid electrolyte layer 40 interposed therebetween. The solid electrolyte layer contains a sulfide solid electrolyte SE but no resin binder and self-maintains its shape by a bonding force of the sulfide solid electrolyte. The solid electrolyte layer has a layer thickness 40T of 50 μm or less and an area 40S of 100 cm2 or more.