An apparatus for manufacturing a multilayered interlayer for safety glass having a first and a second outermost layers and an inserted layer disposed between the first and the second outermost layers, the apparatus comprising: a first extruding machine for delivering a thermoplastic resin composition for the outermost layer formation for forming the first and the second outermost layers; a second extruding machine for delivering a thermoplastic resin composition for the inserted layer formation for forming the inserted layer; a guide for the layer disposition further comprising; a first delivering hole through which the thermoplastic resin composition for the outermost layer formation is delivered, the first delivering hole being connected to the first extruding machine; a second delivering hole through which the thermoplastic resin composition for the inserted layer formation is delivered, the second delivering hole being connected to the second extruding machine; outlets (9, 10) for the first and the second outermost layers formation, the outlets (9, 10) for the first and the second outermost layers formation having a slit shape corresponding to sectional shapes of the first and the second outermost layers; an outlet for the inserted layer formation for forming the inserted layer, the outlet being disposed between the outlets (9, 10) for the first and the second outermost layers formation; flow path for the outermost layer formation connecting the first delivering hole and the outlets (9, 10) for the first and the second outermost layers formation; flow path for the inserted layer formation that connects the second delivering hole and the outlet for the inserted layer formation; characterized in that the apparatus further comprises a metal mold for extruding the interlayer obtained by lamination of the resin compositions for the first and the second outermost layers formation, and the resin composition for the inserted layer formation that have been delivered, the metal mold being connected to the outlets (9, 10) for the first and the second outermost layers formation and the outlet for the inserted layer formation of the guide for the layer disposition, wherein the outlet for the inserted layer formation provided in the guide for the layer disposition has a shape of a slit extending in the width direction of the interlayer, and has a decreasing thickness of the slit with increasing proximity to one end in at least the one end of the shape of a slit. a first extruding machine for delivering a thermoplastic resin composition for the outermost layer formation for forming the first and the second outermost layers; a second extruding machine for delivering a thermoplastic resin composition for the inserted layer formation for forming the inserted layer; a guide for the layer disposition further comprising; a first delivering hole through which the thermoplastic resin composition for the outermost layer formation is delivered, the first delivering hole being connected to the first extruding machine; a second delivering hole through which the thermoplastic resin composition for the inserted layer formation is delivered, the second delivering hole being connected to the second extruding machine; outlets (9, 10) for the first and the second outermost layers formation, the outlets (9, 10) for the first and the second outermost layers formation having a slit shape corresponding to sectional shapes of the first and the second outermost layers; an outlet for the inserted layer formation for forming the inserted layer, the outlet being disposed between the outlets (9, 10) for the first and the second outermost layers formation; flow path for the outermost layer formation connecting the first delivering hole and the outlets (9, 10) for the first and the second outermost layers formation; flow path for the inserted layer formation that connects the second delivering hole and the outlet for the inserted layer formation; characterized in that the apparatus further comprises a metal mold for extruding the interlayer obtained by lamination of the resin compositions for the first and the second outermost layers formation, and the resin composition for the inserted layer formation that have been delivered, the metal mold being connected to the outlets (9, 10) for the first and the second outermost layers formation and the outlet for the inserted layer formation of the guide for the layer disposition, wherein the outlet for the inserted layer formation provided in the guide for the layer disposition has a shape of a slit extending in the width direction of the interlayer, and has a decreasing thickness of the slit with increasing proximity to one end in at least the one end of the shape of a slit.