The invention is directed to providing a semiconductor device receiving a blue-violet laser, of which the reliability and yield are enhanced. A device element converting a blue-violet laser into an electric signal is formed on a front surface of a semiconductor substrate. An optically transparent substrate is attached to the front surface of the semiconductor substrate with an adhesive layer being interposed therebetween. The adhesive layer contains transparent silicone. Since the front surface of the device element is covered by the optically transparent substrate, foreign substances are prevented from adhering to the front surface of the device element. Furthermore, the adhesive layer is covered by the optically transparent substrate. This prevents the adhesive layer from being exposed to outside air, thereby preventing the degradation of the adhesive layer 6 due to a blue-violet laser.