Provided is a forming apparatus which forms an upper surface of adhesive substance to adhere tiles to a laying surface in a ridge-and-groove shape so as to prevent a wavy surface or unintended inclination. The forming apparatus includes tongue forming means having a plurality of tongues and a tongue securing portion; grasping means; and contact means. The tongues have gaps therebetween and a free end protruding from a base end located on a bottom defining line in the protrusion direction perpendicular to the bottom defining line on a tongue existence plane. The base end of the tongues is attached to an edge portion. The grasping means is directly or indirectly attached to the tongue securing portion. The contact means has at least two contact points on a virtual plane perpendicular to the protrusion direction. The two contact points or legs thereof exist on a contact defining line.