PURPOSE: To increase the accuracy to track the incoming direction of solar rays, by receiving good thermal radiation from a solar rays sensor part, by preventing the characteristic of an optical sensor from being deteriorated by the heat received from solar rays, in the titled solar rays directional sensor.

CONSTITUTION: A plurality of optical sensors X1, X2,W are fitted to the bottom plate 4 of a cylindrical body 1, as well as to punch the top plate 2 of the cylindrical body 1 to provide a window 3 to it, in a solar rays directional sensor. The bottom plate 4 is made of a heat transferring body, and a recess 5 is provided in the position of the bottom plate 4, opposed to the window 3 of a top plate 2. On the other hand, an optical sensor XC is put on an insulating base plate 6 having heat transferring property so that the base plate 6 acts to fix the optical sensor XC to the cylindrical body 1, and the recess 5 is closed, having the predetermined distance from the bottom plate 4. As a result, good thermal radiation is obtainable from the XC part of an optical sensor, and the characteristic of an optical sensor XC is prevented from being deteriorated, so that the accuracy of the titled sensor to track the incoming direction of solar rays can be increased.