To provide an optical glass suitable for a glass preform for precision molding having a low glass transition temperature and optical characteristics such as a high refractive index and low dispersion.

The optical glass, having optical characteristics such as a high refractive index and low dispersion, contains cationic components of Si4+, B3+, Zn2+, La3+, Ta5+, Ga3+, and W6+ as essential components and has a refractive index (nd) of 1.8-1.9 and an Abbe number (d) of 35-42. The glass less causes striae and devitrification during fusion outflow. The optical device can be produced from the optical glass.