Abstract: An X-ray radiographing apparatus is provided with an interlock mechanism to avoid mutual interference of movable elements such as an X-ray unit, a compression cone, a table, a tabletop and a spot-film device. When a judging element judges, in response to information outputted from a position detecting element of the movable elements and switches operated by an operator, that interlock should be done, an interlocking element is worked, and then a teaching unit is worked. Thus, the interlocked state itself and how to unlock from the interlocked state can be taught to the operator with graphic images by the teaching unit.