A boom vibration control device that is configured to suppress vibration of a boom that is cantilever-supported on a working vehicle includes a left-roll-direction biasing unit that biases the boom in the left roll direction with respective to the working vehicle and right-roll-direction biasing unit that biases the boom in the right roll direction with respective to the working vehicle. The boom is held at the roll angle at which the biasing force of the left-roll-direction biasing unit and the biasing force of the right-roll-direction biasing unit are balanced.
