Provided is a resin composition containing: a modified polyphenylene ether compound terminally modified with a substituent having an unsaturated carbon-carbon double bond; a cross-linking curing agent having an unsaturated carbon-carbon double bond in its molecule; a silane coupling agent having a phenylamino group in its molecule; and silica. A content of the silica is 60 to 250 parts by mass with respect to a total of 100 parts by mass of the modified polyphenylene ether compound and the cross-linking curing agent.