Abstract: A monitor filter includes a rectangular frame including a first cover and a second cover engaged with the first cover, the first and second covers being of identical structure, each of the first and second covers having two upper corners formed with a semi-cylindrical recess having screw threads such that the rectangular frame will have two threaded holes at two upper corners thereof when the first and second covers are joined together, and a pair of arms each having a bottom provided with a slip-proof material and a downwardly extending screw threadedly engageable with each of the threaded holes, whereby the monitor filter can be adjusted to position right in front of a monitor.