To provide a table folding tuning device which is large in the table folding tuning device of a top plate folding type table and eliminates the interference with the knees of sitting persons while such interference makes the easy sitting infeasible.

Lower pins 21 and part of folding lock mechanisms 8 which are heretofore located in the lower part on the inner side of inside cylinders 3 are arranged on the outer side of the inside cylinders. The bottom ends of coil springs 7 are pressed to the bottom plates 6 of the inside cylinders and the top ends are pressed to the rear surfaces of the connecting pins 2, by which the parts to be built into the inside cylinders 3 are confined only to the coil springs 7. The length of the inside cylinders is this minimized and the size of this device is reduced.