A component-embedded resin substrate (1) includes a plurality of resin layers (2) made of a first resin and laminated on one another, and a component (3) arranged to be surrounded by each resin layer (2) in a first group (8) which is a group of two or more resin layers arranged successively in a thickness direction included in the plurality of resin layers (2). An auxiliary resin portion (9) made of a second resin different from the first resin is arranged to be in contact with and along at least one of surfaces of the component (3).