A tuning element having a second inclined plane interacts with a pushing element having a first inclined plane to accomplish adjusting the position of a printhead. The tuning element rotates relative to a printhead carrier and produces displacement in a second direction and the second inclined plane of the tuning element then pushes the first inclined plane of the pushing element and produces displacement in a first direction in a linear way corresponding to the rotation of the tuning element. Meanwhile, the printhead closely in contact with the pushing element also produces displacement in the first direction so that the tuning apparatus is endowed with highly accurate and linear adjustability.