A treatment device includes a probe to acquire an image of a target using ultrasonic waves, a needle guide provided along the probe, a needle movable along the needle guide, a measurement unit to sense a movement distance of the needle based on contact caused by movement of the needle, and a controller to calculate the movement distance of the needle based on a value measured by the measurement unit. The treatment device may further include a needle sensing unit to determine whether the needle has reached a reference position. The measurement unit is driven based on the determination of the needle sensing unit.
