A heat-curable silicone resin composition comprising: a molten mixture of a resinous organopolysiloxane that has a weight-average molecular weight of 500 to 20,000 in terms of polystyrene, and is represented by the following average composition formula (CH 3) a Si(OR 1) b c O (4-a-b-c)/2 wherein each R 1 represents an identical or different organic group having 1 to 4 carbon atoms, and a, b and c are numbers satisfying 0.8 ≤ a ≤ 1.5, 0 ≤ b ≤ 0.3, 0.001 ≤ c ≤ 0.5 and 0. 801 ≤ a+b+c < 2, and an organopolysiloxane that contains in one molecule at least one cyclohexyl group or phenyl group, and has a linear diorganopolysiloxane residue represented by the following general formula wherein each R 2 independently represents a monovalent hydrocarbon group selected from a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, a cyclohexyl group, a phenyl group, a vinyl group and an allyl group, and m represents an integer of 5 to 50; an inorganic filler added in an amount of 330 to 850 parts by mass, with respect to the total of 100 parts by mass of the components and; a curing catalyst added in an amount of 0.01 to 10 parts by mass, with respect to the total of 100 parts by mass of the organopolysiloxanes as the components and; and a silane coupling agent added in an amount of 0.1 to 8.0 parts by mass, with respect to the total of 100 parts by mass of the components and, wherein the components and are to be cured by a condensation reaction, and a difference between a storage elastic modulus of a cured product of the composition at 25°C and a storage elastic modulus of the cured product of the composition at 150°C is not larger than 4,000 MPa, wherein the cured product is prepared by performing molding at a molding temperature of 150°C and under a molding pressure of 6.9 N/mm 2 for a molding time of 300 sec using a mold manufactured in accordance with JIS K6911:2006, and then performing post curing at 150°C for 4 hours, while the storage elastic modulus is measured at a temperature rising rate of 10°C/min and within a temperature range of 0 to 200°C. a resinous organopolysiloxane that has a weight-average molecular weight of 500 to 20,000 in terms of polystyrene, and is represented by the following average composition formula (CH 3) a Si(OR 1) b c O (4-a-b-c)/2 wherein each R 1 represents an identical or different organic group having 1 to 4 carbon atoms, and a, b and c are numbers satisfying 0.8 ≤ a ≤ 1.5, 0 ≤ b ≤ 0.3, 0.001 ≤ c ≤ 0.5 and 0. 801 ≤ a+b+c < 2, and an organopolysiloxane that contains in one molecule at least one cyclohexyl group or phenyl group, and has a linear diorganopolysiloxane residue represented by the following general formula wherein each R 2 independently represents a monovalent hydrocarbon group selected from a hydroxyl group, an alkyl group having 1 to 3 carbon atoms, a cyclohexyl group, a phenyl group, a vinyl group and an allyl group, and m represents an integer of 5 to 50; an inorganic filler added in an amount of 330 to 850 parts by mass, with respect to the total of 100 parts by mass of the components and; a curing catalyst added in an amount of 0.01 to 10 parts by mass, with respect to the total of 100 parts by mass of the organopolysiloxanes as the components and; and a silane coupling agent added in an amount of 0.1 to 8.0 parts by mass, with respect to the total of 100 parts by mass of the components and, wherein the components and are to be cured by a condensation reaction, and a difference between a storage elastic modulus of a cured product of the composition at 25°C and a storage elastic modulus of the cured product of the composition at 150°C is not larger than 4,000 MPa, wherein the cured product is prepared by performing molding at a molding temperature of 150°C and under a molding pressure of 6.9 N/mm 2 for a molding time of 300 sec using a mold manufactured in accordance with JIS K6911:2006, and then performing post curing at 150°C for 4 hours, while the storage elastic modulus is measured at a temperature rising rate of 10°C/min and within a temperature range of 0 to 200°C.