Provided is a resin composition that can provide a cured product of low dielectric tangent, high mechanical strength, and high adhesiveness. The resin composition contains (A) a resin having a thermosetting functional group FA, (B) a resin having a radical polymerizable functional group FB, and (C) a resin having a functional group FA′ reacting with the thermosetting functional group FA and a functional group FB′ reacting with the radical polymerizable functional group FB. A number na of the functional group FA′ of the component (C) when the number of the thermosetting functional group FA of the component (A) is defined as 1 and a number nb of the functional group FB′ of the component (C) when the number of the radical polymerizable functional group FB of the component (B) is defined as 1 satisfy 0.01≤na≤200 and 0.01≤nb≤400, respectively.