An electronic component embedded substrate 1 includes a substrate 10 having a wiring layer 11 and an insulating layer 12; an electronic component 20 built in the substrate 10, and having a pair of electrode layers 21A and 21B, and a dielectric layer 22; and a stress relieving layer 30 provided closer to the wiring layer 11 than the insulating layer 12 is in the lamination direction, wherein at least part of an end portion of the electronic component 20 on the wiring layer 11 side is in contact with the stress relieving layer 30, wherein at least part of an end portion of the electronic component 20 on the insulating layer 12 side is in contact with the insulating layer 12, and wherein the Young's modulus of the stress relieving layer 30 is lower than the Young's modulus of the electrode layer 21B.