To mold a quality concrete product without generating noise.

To apply a vibration of narrow amplitude to a form horizontally for a short period, fundamentally in a vibrator, wheels 3 with a dolly is placed between the concrete form 1 and a base 2, and a motor 4 for vibration is fixed on the base 2 of the form 1. The motor 4 is connected to a change gear 5 and inclined rotary plate 6, a ball joint 7 is mounted on the rotary plate 6 and brought into loose contact with a rotary rod 8. The rotary rod 8 is fixed to the form 1 through an adjustable joint 9 and a slide shaft 11. Namely, the rotation of a driving motor is converted into horizontal movement by the rotary plate 6 to vibrate the form. The simultaneous setting of the amplitude and the period is done by connecting the rotary plate 6 to a belt adjusting plate.