an ink jet recording apparatus composed of a print head of the on - demand type for ejecting an ink droplet according to print data and a platen having a flat section opposed to the head and extending at least over a region corresponding to a printing span through which the head is displaced to effect printing . the flat section of the platen is formed with a plurality of opening holes each having a relatively small diameter . a vacuum device creates a vacuum beneath the platen to attract a recording medium onto the flat section to enable the recording medium to receive ink droplets ejected from the head so as to print an image . the dimensions or the density of the opening holes is gradually reduced so as to compensate for differences in width of the recording media to thereby effectively avoid floating of a medium .