The invention provides an electro-optical device, comprising: a substrate; an optical waveguide composed of an electro-optic material film formed in a ridge shape on the substrate; a buffer layer configured to cover the optical waveguide; and an upper electrode provided on the optical waveguide through the buffer layer, and the buffer layer has a recess on the upper electrode side above the optical waveguide. According to the electro-optical device of the present invention, the propagation loss of light can be suppressed.