The invention relates to a lock device comprising a key and a lock cylinder, said lock cylinder comprising a fixed cylinder housing and a cylinder core mounted to rotate therein. The key shaft (10.3) has an edge profile and may be inserted in a key way of the cylinder core in which displaceable tumblers (41, 42) are located transverse to the above. The key shaft (10.3) has profiled recesses running in the longitudinal direction, comprising a pair of follow points for each tumbler (41, 42) for coding the key, whilst the tumbler (41, 42) has a pair of counter follow points which are the basis of the corresponding counter coding. According to this invention, a space-saving design of the lock device may be achieved with a large range of variation for the coding wherein both follow points are on the key shaft (10.3) in the form of recesses, arranged on opposing lateral surfaces to an edge (57.2; 57.3) of the edge profile of the key shaft (10.3). A web (22; 23) is thus generated in the corner region of the edge profile between both recesses. Said web functions a code web (22; 23), as the opposing web edges serve for the coding. The corresponding tumblers (41, 42) have a cut-out, which in use enclose the code web (22; 23) on opposing web edges. The lateral limits of the cut-out form the counter follow points in the tumblers (41, 42).