An electronic component integrated substrate includes a first substrate including a first pad, a first solder resist layer provided with a first open portion that selectively exposes the first pad, and a connection pad formed on the first solder resist layer, and electrically connected to the first pad; a second substrate, stacked on the first substrate, including a second pad, and a second solder resist layer formed on the second pad and provided with a second open portion that selectively exposes the second pad; an electronic component mounted on the first substrate and sandwiched between the first substrate and the second substrate; and a substrate connection member that electrically connects the connection pad and the second pad with each other, the diameter of the connection pad being larger than each of the diameter of the first pad and the diameter of the second open portion.