An optical pickup device includes a light source emitting a light beam having a wavelength within a range of 390 nm to 420 nm and an optical element to perform recording and/or reproducing of information of an optical disk having a protective substrate thickness d.sub.1 mm using the first light beam from the first light source, wherein the optical element is made of a mixed material produced by dispersing particles into a resin, a sign of a refractive index change .DELTA.n.sub.2/.DELTA.t of the particles owing to a temperature change is opposite to a sign of a refractive index change .DELTA.n.sub.1/.DELTA.t of the resin owing to a temperature change, or an absolute value of the refractive index change .DELTA.n.sub.2/.DELTA.t is smaller than an absolute value of the refractive index change .DELTA.n.sub.1/.DELTA.t.