A substrate with built-in electronic component includes: a core layer that includes a core material and a cavity formed in the core material and containing an insulating material; an insulating layer that includes a ground wiring and a signal wiring and is formed on the core layer; and a plurality of electronic components that each include a first terminal and a second terminal and are stored in the cavity, the plurality of electronic components each having one end portion and the other end portion, the first terminal being formed at the one end portion and connected to the ground wiring, the second terminal being formed at the other end portion and connected to the signal wiring, the plurality of electronic components having at least one of arrangements in which the first terminals face each other and in which the second terminals face each other.