An optical sensor device comprises an element-mounting portion, an optical sensor element provided on the element-mounting portion, a lead having a first contact region connected to the optical sensor element and a second contact region for an external connection, and a resin-encapsulating portion which covers at least a light-receiving plane of the optical sensor element. The resin-encapsulating portion comprises a resin and a glass filler including borosilicate glass dispersed in the resin. The transmissivity of the resin-encapsulating portion in one example is equal to or more than 40% in a wavelength range between 300 nm to 400 nm, and in another example is equal to or more than 60% in a wavelength range between 300 nm and 350 nm.