An optical sensor apparatus includes a package having a window; a sensor chip having an array of light receiving devices and a pixel electrode connected to each light receiving device, the sensor chip having an incidence surface that faces the window of the package; and a read-out circuit disposed under the sensor chip, the read-out circuit having a read-out electrode electrically connected to each pixel electrode of the sensor chip. The sensor chip and the read-out circuit are housed in the package. In plan view from the sensor chip, the read-out circuit is overlapped by the sensor chip, and the read-out circuit has no portion extending off the sensor chip.