PURPOSE: To prevent a lubricating oil from evaporation, to ensure lubrication of guide pins and to prolong the life of a mold by forming an oil storage room in the guide pin and opening a valve and communicating the oil storage room outside when the guide pin is entered into a guide hole.

CONSTITUTION: Guide pins 15 are provided on four corners of an upper adapter plate 11 to make it possible to enter the guide pins into guide holes 16A of guide bushes 16 fixed on a lower mold plate 14. A stepped hole 15A and a stepped hole 15B in the radial direction communicating therewith are graved in the central part of the guide pin 15 and an oil nipple 20 is screwed thereinto to form an oil storage room in the guide pin 15. When the upper mold plate 12 is lowered, a ball valve 20A of the oil nipple 20 is opened against a spring 20B by the wall face of the guide hole 16A to feed a lubricating oil in the oil storage room into the guide hole 16A. In addition, when the ball valve 20A is fitted to a cyclic groove 16B of a guide bush 16, the oil nipple is closed to shut the communication and to prevent the lubricating oil from unnecessary feeding. In addition, when the upper and the lower molds are separated, it is closed similarly.