A fiber-reinforced plastic producing device comprising: a molding die having a first placement surface for the placement of a fabric and a formation surface having a predetermined angle with respect to the first placement surface; and a movable stage (11;12) including a plate part having a second placement surface for the placement of an end side of the fabric, the movable stage (11;12) disposed adjacent to the molding die; wherein the movable stage (11;12) is configured so that the second placement surface thereof can form a continuous plane with the first placement surface and can move below the first placement surface after being inclined with respect to the first placement surface, characterized in that the movable stage (11;12) further includes a leg part which is provided with first and second rod-like members (14A,14B) connected in the height direction, which supports the plate part and which is configured to contract in a height direction of the molding die, a first connection part connecting the plate part and the first rod-like member of the leg part so that the plate part with the second placement surface can rotate with respect to the first rod-like member of the leg part, a second connecting part to which the first and second rod-like members (14A,14B) are connected so that the first and second rod-like members (14A,14B) can rotate relative to each other, a third connection part to which a fixing part for fixing the movable stage (11;12) and the second rod-like member are connected so that the second rod-like member can rotate relative to the fixing part, a first elastic member which is provided on the first connection part to support the plate part so that the second placement surface thereof forms the continuous plane with the first placement surface until a predetermined load is applied, and a second elastic members (17A,18A) which are respectively provided on the second and third connection part (17,18) of the leg part to maintain the height of the leg part until a predetermined load is applied, wherein an elastic force of the first elastic member is lower than an elastic force of the second and third elastic member (17A,18A). a molding die having a first placement surface for the placement of a fabric and a formation surface having a predetermined angle with respect to the first placement surface; and a movable stage (11;12) including a plate part having a second placement surface for the placement of an end side of the fabric, the movable stage (11;12) disposed adjacent to the molding die; wherein the movable stage (11;12) is configured so that the second placement surface thereof can form a continuous plane with the first placement surface and can move below the first placement surface after being inclined with respect to the first placement surface, characterized in that the movable stage (11;12) further includes a leg part which is provided with first and second rod-like members (14A,14B) connected in the height direction, which supports the plate part and which is configured to contract in a height direction of the molding die, a first connection part connecting the plate part and the first rod-like member of the leg part so that the plate part with the second placement surface can rotate with respect to the first rod-like member of the leg part, a second connecting part to which the first and second rod-like members (14A,14B) are connected so that the first and second rod-like members (14A,14B) can rotate relative to each other, a third connection part to which a fixing part for fixing the movable stage (11;12) and the second rod-like member are connected so that the second rod-like member can rotate relative to the fixing part, a first elastic member which is provided on the first connection part to support the plate part so that the second placement surface thereof forms the continuous plane with the first placement surface until a predetermined load is applied, and a second elastic members (17A,18A) which are respectively provided on the second and third connection part (17,18) of the leg part to maintain the height of the leg part until a predetermined load is applied, wherein an elastic force of the first elastic member is lower than an elastic force of the second and third elastic member (17A,18A).