PURPOSE: To reduce the parts and components and to simplify the operation by making an universal assembly adaptable to an upper latch and a bottom latch only by adding parts and the like, and operating the latch by pushing or retracting a rod.

CONSTITUTION: An universal assembly 10 for top and bottom latches comprises a platform comprising a base part 14 and a side wall 16, an input member 28 comprising a retracting pin 26 and a pushing pin 28, a sub-assembly 42 comprising a spring 38, a rod connecting member 18 and a link 24, a blocking arm 60 and the like. The universal assembly can be convertible to both functions of an upper latch and a bottom latch only by independently adding the parts and components. One end of the link 24 of the universal assembly 10 is engaged with the pin 26 or 30, the rod 32 is retracted or pushed to push a latch bolt to operate the upper or bottom latch.