The invention relates to an aiming, or targeting, device which is used to guide and place longitudinal bone fixing means in a predetermined direction with respect to a bone fixing device. The aiming device includes securing means, which can be detachably secured to a bone fixing device, a first centering part, which can be placed on the bone fixing device, and a second centering part, which is arranged at a distance from the first centering part. Both of the centering parts include at least one pair of guiding elements which are arranged in a coaxial manner in relation to each other.