There is provided a method and a device for accurately detecting the contact of a mechanical probe with a contact object. The contact detecting device comprises a mechanical probe movable for being in contact with a contacted object, a charged particle beam source which generates a charged particle beam applied to the contacted object, a detector for detecting secondary particles or reflected particles from the contacted object, a calculating device which calculates, from a detection signal from the detector, a feature quantity of a shadow of the mechanical probe projected on the contacted object, and a control device which controls the operation of the mechanical probe. The calculating device calculates, as the feature quantity of the shadow of the mechanical probe, a shadow depth S(x, y), and obtains an evaluation value J(z), showing a distance between the contacted object and the mechanical probe, based on the shadow depth S(x, y).