PURPOSE: To provide an auxiliary top board apparatus which is inexpensive with a simple structure and moreover, has better operability.

CONSTITUTION: A fixed frame 1 is fixed on the undersurface of a main top board A. A lift frame 2 is pivoted on the fixed frame 1 free to turn. An auxiliary top board support frame 3 is pivoted on the lift frame 2 free to turn. When a handle 52 for lift adjustment is turned by a manual operation, a screw bar 51 turns. A lift rod 4 having a screw hole to be screwed down on the screw bar 51 turns the rotation of the screw bar 51 to a thrust and then, the motion is transmitted to the lift frame 2. The lift frame 2 turns centered on pins 1d and 1d' and the auxiliary top board support frame 3 moves upward or downward along a circular orbit with the rotary motion of the lift frame 2. As a result, the height of an auxiliary top board B changes as supported on the top surface, of the auxiliary top board support frame 3. The auxiliary top board support frame 3 is clamped on the lift frame 2 at an arbitrary angle position by turning a handle 6 for slant fixing. Thus, an angle of inclination of the auxiliary top board B is adjusted.