The present invention provides an ultraviolet detecting device which comprises a silicon semiconductor layer having a thickness ranging from greater than or equal to 3 nm to less than or equal to 36 nm, which is formed over an insulating layer, lateral PN-junction type first and second photodiodes formed in the silicon semiconductor layer, an interlayer insulating film formed over the silicon semiconductor layer, a first filter layer made of silicon nitride, which is formed over the interlayer insulating film provided over the first photodiode and causes light lying in a wavelength range of an UV-B wave or higher to pass therethrough, and a second filter layer made of silicon nitride, which is formed over the interlayer insulating film provided over the second photodiode and allows light lying in a wavelength range of an UV-A wave or higher to pass therethrough.