This invention concerns a system for aligning a simulator (3) arranged for firing and mounted on a weapon. The simulator has a radiation source (8) arranged so as to emit a beam along a simulation axis, and adjusting means (10) for adjusting the simulation axis so that it is aligned with the weapon sight. The system is characterized in that it includes a sighting mark at which the weapon sight is to be aimed during alignment, and means arranged in connection with the sighting mark to emit a beam along an axis representing an aligned simulation axis. The system further includes an aligning unit (14) that is deployable at the simulator and in which at least a first part of the beam from the element (8) is reflected along an axis representing the current position of the simulation axis. Position-indicating means (18) are arranged so that the beam alone the axis representing the aligned beam strikes the position-indicating means (18) at a point representing a set-point value for the simulation axis, and so that the beam along the axis representing the current simulation axis strikes the position-indicating means at a point representing an actual value for the simulation axis.