A resin composition comprising: a silicone resin containing a constitutional unit shown by the following composition formula and having a weight average molecular weight of 3,000 to 500,000, wherein R 1 to R 4 each independently represent a monovalent hydrocarbon group having 1 to 8 carbon atoms, with the proviso that the both of R 3 and R 4 are not methyl groups at the same time; "m" and "n" are each independently an integer of 0 to 300; the both of "a" and "b" are positive numbers satisfying a+b = 1; each of "X" independently represents a linking group selected from the divalent groups shown by the following general formulae,,, and, and when the molar numbers of units shown by the following general formulae,,, and contained in the silicone resin are defined as "c", "d", "e", and "f" respectively, "e" is a positive number, each of "c", "d", and "f" is 0 or a positive number satisfying c+d+e+f/the molar number of the linking group shown by "X" contained in the silicone resin = 1, and having a ratio to "e" in a range of c+d = 1 to 10 and f = 0 to 1 when the "e" is assumed to be 1; wherein "V" is a divalent organic group selected from the following -CH 2 -, "p" is 0 or 1, R 5 represents a hydrogen atom or a methyl group, "g" is an integer of 0 to 7, R 6 and R 7 each independently represent the same or different group selected from alkyl groups and alkoxy groups having 1 to 4 carbon atoms, and "h" is any of 0, 1, and 2, wherein R 8 represents a hydrogen atom or a methyl group, and "q" is an integer of 0 to 7, wherein "Y" is a divalent group selected from the following wherein "R" each independently represent a hydrogen atom or a methyl group, and R 9 and R 10 each independently represent a hydrogen atom or a methyl group, wherein R 12 and R 13 each independently represent a monovalent hydrocarbon group having 1 to 8 carbon atoms, with the proviso that the both of R 12 and R 13 are not methyl groups at the same time, "r" and "s" are each independently an integer of 0 to 300, R 11 represents a hydrogen atom or a methyl group, and "k" is an integer of 0 to 7; an epoxy resin-curing agent; and a filler, wherein the amount of the component is 5 to 50 parts by mass based on 100 parts by mass of the component, and the mass fraction of the component is 50 to 95% by mass based on the total mass. a silicone resin containing a constitutional unit shown by the following composition formula and having a weight average molecular weight of 3,000 to 500,000, wherein R 1 to R 4 each independently represent a monovalent hydrocarbon group having 1 to 8 carbon atoms, with the proviso that the both of R 3 and R 4 are not methyl groups at the same time; "m" and "n" are each independently an integer of 0 to 300; the both of "a" and "b" are positive numbers satisfying a+b = 1; each of "X" independently represents a linking group selected from the divalent groups shown by the following general formulae,,, and, and when the molar numbers of units shown by the following general formulae,,, and contained in the silicone resin are defined as "c", "d", "e", and "f" respectively, "e" is a positive number, each of "c", "d", and "f" is 0 or a positive number satisfying c+d+e+f/the molar number of the linking group shown by "X" contained in the silicone resin = 1, and having a ratio to "e" in a range of c+d = 1 to 10 and f = 0 to 1 when the "e" is assumed to be 1; wherein "V" is a divalent organic group selected from the following -CH 2 -, "p" is 0 or 1, R 5 represents a hydrogen atom or a methyl group, "g" is an integer of 0 to 7, R 6 and R 7 each independently represent the same or different group selected from alkyl groups and alkoxy groups having 1 to 4 carbon atoms, and "h" is any of 0, 1, and 2, wherein R 8 represents a hydrogen atom or a methyl group, and "q" is an integer of 0 to 7, wherein "Y" is a divalent group selected from the following wherein "R" each independently represent a hydrogen atom or a methyl group, and R 9 and R 10 each independently represent a hydrogen atom or a methyl group, wherein R 12 and R 13 each independently represent a monovalent hydrocarbon group having 1 to 8 carbon atoms, with the proviso that the both of R 12 and R 13 are not methyl groups at the same time, "r" and "s" are each independently an integer of 0 to 300, R 11 represents a hydrogen atom or a methyl group, and "k" is an integer of 0 to 7; an epoxy resin-curing agent; and a filler, wherein the amount of the component is 5 to 50 parts by mass based on 100 parts by mass of the component, and the mass fraction of the component is 50 to 95% by mass based on the total mass.