A gate valve (30; 130; 230) configured to have an injection hole formed therein and switched over to allow or block a flow of a thermosetting resin via the injection hole, the gate valve comprising: a casing (40; 140) configured to have a specific space formed inside thereof to be extended along a specified direction; a gate valve pin (50; 150; 250) configured to be movable in the specified direction in the specific space; and characterized by a sleeve provided outside of the gate valve pin (50; 150; 250) in the specific space and configured to be movable in the specified direction, wherein the gate valve (30; 130; 230) is configured to have a first fluid flow path (57; 249), wherein in a state where the gate valve pin (50; 150; 250) is at a first pin position, a front end section on an injection hole side of the gate valve pin (50; 150; 250) closes the injection hole to block communication between the first fluid flow path (57; 249) and the injection hole, in a state where the gate valve pin (50; 150; 250) is at a second pin position that is more distant from the injection hole than the first pin position, the front end section opens the injection hole to make communication between the first fluid flow path (57; 249) and the injection hole and thereby form a resin supply line (57, 47, 81) for allowing the flow of the thermosetting resin, in a state where the sleeve is at a first sleeve position and the gate valve pin is at the first pin position, a second fluid flow path (70; 170; 270) is formed in the gate valve (30; 130; 230) to connect an injection hole-side end of the first fluid flow path (57; 249) to outside of the gate valve (30; 130; 230) and is made to communicate with the first fluid flow path (57; 249) and thereby form a cleaning line for supplying and discharging a cleaning liquid, and in a state where the sleeve is at a second sleeve position that is closer to the injection hole than the first sleeve position, the sleeve blocks communication between the first fluid flow path (57; 249) and the second fluid flow path (70; 170; 270) connecting to the outside. a casing (40; 140) configured to have a specific space formed inside thereof to be extended along a specified direction; a gate valve pin (50; 150; 250) configured to be movable in the specified direction in the specific space; and characterized by a sleeve provided outside of the gate valve pin (50; 150; 250) in the specific space and configured to be movable in the specified direction, wherein the gate valve (30; 130; 230) is configured to have a first fluid flow path (57; 249), wherein in a state where the gate valve pin (50; 150; 250) is at a first pin position, a front end section on an injection hole side of the gate valve pin (50; 150; 250) closes the injection hole to block communication between the first fluid flow path (57; 249) and the injection hole, in a state where the gate valve pin (50; 150; 250) is at a second pin position that is more distant from the injection hole than the first pin position, the front end section opens the injection hole to make communication between the first fluid flow path (57; 249) and the injection hole and thereby form a resin supply line (57, 47, 81) for allowing the flow of the thermosetting resin, in a state where the sleeve is at a first sleeve position and the gate valve pin is at the first pin position, a second fluid flow path (70; 170; 270) is formed in the gate valve (30; 130; 230) to connect an injection hole-side end of the first fluid flow path (57; 249) to outside of the gate valve (30; 130; 230) and is made to communicate with the first fluid flow path (57; 249) and thereby form a cleaning line for supplying and discharging a cleaning liquid, and in a state where the sleeve is at a second sleeve position that is closer to the injection hole than the first sleeve position, the sleeve blocks communication between the first fluid flow path (57; 249) and the second fluid flow path (70; 170; 270) connecting to the outside.