An electronic component-embedded substrate includes a wiring structure including a plurality of insulating layers and a plurality of wiring layers and having a cavity penetrating through at least one of the plurality of insulating layers, a first electronic component disposed in the cavity, a dam structure disposed on the wiring structure and having a through-portion, a first insulating material disposed in at least a portion of each of the cavity and the through-portion, and covering at least a portion of each of the wiring structure and the first electronic component, and a first circuit layer disposed on the first insulating material.