To provide a desktop panel system in which a stack-on panel can be stacked on a base panel without causing non-uniformity in appearance nor increasing the kinds of constituting members unnecessarily.

The desktop panel system P includes: a base panel 1 attached onto a desk using attaching supports 2; and one or more stack-on panels 3 stacked on the base panel 1 using stacking supports 4. The base panel 1 and the stack-on panel 3 include vertical frame materials 11, 31 having the same flat cross section and including vertically communicating first hollows 11a, 31a and second hollows 11b, 31b on respective both sides respectively. The attaching supports 2 are inserted into the first hollows 11a of the base panel 1 and the stacking supports 4 are inserted into the second hollows 11b of the base panel 1 and the second hollows 31b of the stack-on panel 3.