Provided is a forming device for forming an adhesive composition so that tiles can be reliably laid on a laying surface. A forming device for forming an adhesive composition into a ridged shape in a laying surface on which tiles are laid is characterized by being provided with: a stationary blade (40a) in which a plurality of plate-shaped tongue parts are disposed in a planar fashion, and the respective base ends of the tongue parts are linearly arranged with a gap having a predetermined length therebetween; a graspable main body (21) which secures the stationary blade and is disposed on the stationary blade so as to be movable sideways while pressing the stationary blade from above; a storage space (70) which is defined on the underside of the main body (21) and on the traveling direction side of the lateral movement of the stationary blade (40a); a weir member (81) which is affixed to the main body (21) or the stationary blade (40a) so as to be movable relative to the stationary blade (40a), and is able to
