A vibration generating device includes: a trough where a workpiece is placed; a first vibration motor and a second vibration motor whose rotary shafts are laid along a horizontal direction and parallel to each other; a transmission unit where the first vibration motor and the second vibration motor are arranged and that transmits a vibration of the first vibration motor and the second vibration motor to the trough; a first sensor detecting a rotating position of the rotary shaft of the first vibration motor; and a second sensor detecting a rotating position of the rotary shaft of the second vibration motor.