Evaporated fuel processing device

An evaporated fuel processing device comprising a canister (1) which accommodates an adsorbent material to temporarily collect fuel vapors, volume compensator means (4) to keep said adsorbent material in a compact state, a tank port (5), a purge port (6), and at least one buffer tube (7) connected to either tank or purge port so as to forcibly pass fuel vapors through the adsorbent material, said buffer tube (7) extending through an aperture in said volume compensator means (4) into the adsorbent material. According to the invention, the volume compensator means (4) comprises a tubular element (8) associated with each buffer tube (7), comprising a first opening for slidably receiving said buffer tube into said tubular element so that the pressure drop through the clearance between buffer tube and tubular element is higher than the pressure drop through said adsorbent material, and a second opening for the passage of said fuel vapors.