An organosiloxane resin composition comprising: colloidal silica, a hydrolysis condensate of an alkoxysilane represented by the following formula: R 1 m R 2 n Si(OR 3) 4-m-n wherein R 1 and R 2 are each independently an alkyl group having 1 to 4 carbon atoms, vinyl group or alkyl group having 1 to 3 carbon atoms which is substituted by at least one group selected from the group consisting of methacryloxy group, amino group, glycidoxy group and 3,4-epoxycyclohexyl group, R 3 is an alkyl group having 1 to 4 carbon atoms or vinyl group, m and n are each independently an integer of 0, 1 or 2, and (m + n) is an integer of 0, 1 or 2; and a metal oxide, all of which are dissolved and/or dispersed in a solvent, and (i) the content of the component is 10 to 60 wt% and the content of the component is 40 to 90 wt% based on 100 wt% of the total of the components and when the weight of the component is a weight in terms of R 1 m R 2 n SiO (4-m-n)/2, and the amount of the component is 0.1 to 15 parts by weight based on 100 parts by weight of the total of the components and, and (ii) when the cumulative 50 % particle diameter and cumulative 90 % particle diameter in the laser diffraction particle size distribution measurement of the component are represented by D50 and D90, respectively, D90 is 100 nm or less and D90/D50 is 20 or less. colloidal silica, a hydrolysis condensate of an alkoxysilane represented by the following formula: R 1 m R 2 n Si(OR 3) 4-m-n wherein R 1 and R 2 are each independently an alkyl group having 1 to 4 carbon atoms, vinyl group or alkyl group having 1 to 3 carbon atoms which is substituted by at least one group selected from the group consisting of methacryloxy group, amino group, glycidoxy group and 3,4-epoxycyclohexyl group, R 3 is an alkyl group having 1 to 4 carbon atoms or vinyl group, m and n are each independently an integer of 0, 1 or 2, and (m + n) is an integer of 0, 1 or 2; and a metal oxide, all of which are dissolved and/or dispersed in a solvent, and (i) the content of the component is 10 to 60 wt% and the content of the component is 40 to 90 wt% based on 100 wt% of the total of the components and when the weight of the component is a weight in terms of R 1 m R 2 n SiO (4-m-n)/2, and the amount of the component is 0.1 to 15 parts by weight based on 100 parts by weight of the total of the components and, and (ii) when the cumulative 50 % particle diameter and cumulative 90 % particle diameter in the laser diffraction particle size distribution measurement of the component are represented by D50 and D90, respectively, D90 is 100 nm or less and D90/D50 is 20 or less. (i) the content of the component is 10 to 60 wt% and the content of the component is 40 to 90 wt% based on 100 wt% of the total of the components and when the weight of the component is a weight in terms of R 1 m R 2 n SiO (4-m-n)/2, and the amount of the component is 0.1 to 15 parts by weight based on 100 parts by weight of the total of the components and, and (ii) when the cumulative 50 % particle diameter and cumulative 90 % particle diameter in the laser diffraction particle size distribution measurement of the component are represented by D50 and D90, respectively, D90 is 100 nm or less and D90/D50 is 20 or less.