To provide a mold-in forming locking member permitting bending of a hook locking member so that the hook locking member is fitted for a complicated two-dimensional or three-dimensional structure of a mold in mold-in forming, excellent in the close adhesion to a recess set inside a metal mold, without a risk of losing the engagement function as an engagement element surface is covered by penetration of a foam forming resin liquid.

In the mold-in forming locking member, engagement elements made of hard resin are raised in lines in the length direction of a rod-shaped body on the surface of the rod-shaped body made of an elastomer resin, and a plurality of lines of these engagement elements are present on the surface of the rod-shaped body. The engagement elements constituting each engagement element line are integrated in the direction of the line, and the adjacent engagement element lines are independently present.