To provide a low-thermal expansion resin composition containing silica fillers and an electronic part of high reliability.

The low-thermal expansion resin composition comprises silica particles having ≥6 μmol/g and ≤5 μmol/g isolated silanol groups having an absorption wavelength at about 3740 cm-1 by an infrared spectral measurement. The electronic part is obtained by including a semiconductor element therein and molding the low-thermal expansion resin composition. Thereby, the resin composition having ≥6 μmol/g active lone silanol groups and filled with the silica filler has excellent fluidity and exhibits a lower coefficient of thermal expansion for the same amount of the filled silica. The reliability of the electronic part to which the silica is applied is raised.