A ceiling board for use in a ceiling wherein, in a position of use, a transition between the ceiling board and another ceiling board mating with the ceiling board appears inconspicuous, the ceiling board comprising: a first surface for facing an interior of a room, and a second surface opposite the first surface for abutting against a supporting structure; and four side portions (5, 7, 9, 11) defining the first and second surfaces (3, 4), wherein the side portions comprise a first side portion and a second side portion complementary to and opposite the first side portion, and a third side portion and fourth side portion complementary to and opposite the third side portion, wherein the side portions are in the form of a tongue and groove arrangement adapted to provide a force fit coupling means for allowing a plurality of boards (1, 1') to be lockingly interconnected, wherein a lower end face of the tongue, and a lower portion of an end face of a lip of the groove are perpendicular to the first surface of the ceiling board wherein the first surface of ceiling board is further provided with a wallpaper comprising non-woven fibers, the wallpaper being adhered to said first surface, characterized in that the tongue and groove arrangement of the four side portions (5,7, 9, 11) and a periphery of the wall paper has been concurrently formed in a milling process wherein the periphery of the wallpaper is bevelled with respect to the end face of the lip of the groove and the end face of the tongue, from a visual portion of the wall paper towards a contact face between the wall paper and the first surface, wherein at least some fibers at a periphery of the wallpaper protrude beyond the end faces (58, 78) of the groove and the tongue of the ceiling board, so that, in a position of use of the ceiling board, the at least some fibers interdigitate with at least some fibers protruding from the another mating ceiling board. a first surface for facing an interior of a room, and a second surface opposite the first surface for abutting against a supporting structure; and four side portions (5, 7, 9, 11) defining the first and second surfaces (3, 4), wherein the side portions comprise a first side portion and a second side portion complementary to and opposite the first side portion, and a third side portion and fourth side portion complementary to and opposite the third side portion, wherein the side portions are in the form of a tongue and groove arrangement adapted to provide a force fit coupling means for allowing a plurality of boards (1, 1') to be lockingly interconnected, wherein a lower end face of the tongue, and a lower portion of an end face of a lip of the groove are perpendicular to the first surface of the ceiling board wherein the first surface of ceiling board is further provided with a wallpaper comprising non-woven fibers, the wallpaper being adhered to said first surface, characterized in that the tongue and groove arrangement of the four side portions (5,7, 9, 11) and a periphery of the wall paper has been concurrently formed in a milling process wherein the periphery of the wallpaper is bevelled with respect to the end face of the lip of the groove and the end face of the tongue, from a visual portion of the wall paper towards a contact face between the wall paper and the first surface, wherein at least some fibers at a periphery of the wallpaper protrude beyond the end faces (58, 78) of the groove and the tongue of the ceiling board, so that, in a position of use of the ceiling board, the at least some fibers interdigitate with at least some fibers protruding from the another mating ceiling board.