It is known that when recycled materials are recycled, the mechanical properties are deteriorated with an increase in the thermal history. In particular, in a composite material containing reinforcing fibers, the fiber length becomes shorter each time recycling As a result, the mechanical property deterioration due to the increase in the thermal history is remarkable as compared with the neat resin. For this reason, there are cases in which recycling is prohibited by the user's judgment on composite materials containing glass fiber, but it is regarded as a problem because it gives a negligible effect on cost and environmental impact . In this research, we focused on short residence time and low shear of the vent molding machine, and in response to the possibility that the glass fiber reinforced raw material does not remarkably deteriorate the mechanical properties due to recycling, the glass fiber reinforced raw material by vent molding The change of mechanical properties at recycling was studied.