A reel table moving mechanism selectively receives tape cassettes having different sizes. The mechanism includes a deck member in which a head drum and a tape guiding unit are installed and having first and second openings formed to be spaced from each other, each having a predetermined length. A pair of reel tables, operative to move along the first and second openings, selectively receive first and second tape cassettes of a different size. Each reel table has a stopper for locking a pair of reels and a releasing lever for releasing the stopper. A pair of first and second reel bases on which the reel tables are mounted are slidably supported to the deck member. First and second shafts are supported by a supporting mechanism at one side of each of the first and second openings and are slidably connected to the first and second bases. A mechanism moves the first and second reel bases, and first and second releasing devices release each releasing lever of the first and second tape cassettes from being locked. According to the above mechanism, the structure is simplified, and the reel table can be stably maintained.