PURPOSE: To suppress the fluctuation of electrical characteristics essential as a device and to contrive the improvement of the reliability of the device by a method wherein a function element easy to generate the fluctuation of its characteristics is arranged on the surface region other than a part, which is located under a circumferential wall, of the surface of a chip.

CONSTITUTION: A circumferential wall 3 is formed on the surface of a chip 2 containing a photodetector in such a way as to encircle the element, and is covered with a light-transmitting window material 4. The chip 2 is die-bonded on a lead frame, bonding pads, the lead frame are electrically connected to each other, and the whole is resin-sealed. In this case, a functional element easy to generate the fluctuation of its characteristics is arranged on the part other than a part, which is located under the wall, of the surface of the chip. That is, by arranging the functional element, which is easy to generate the fluctuation of its characteristics, on the part other than a part, which is located under the wall, of the chip surface, a stress to concentrate on the part, which is located under the wall, of the chip surface can be prevented from extending to the functional element. Thereby, an electrical stability essential as a device can be reliably held.