Abstract: A lock for fire-escape door provided with an actuating member having an integrally formed tongue to block the retraction of a main latch from a protruded position provides higher security to the lock. The lock includes: a housing; a pivotable main latch and a pivotable auxiliary latch which are urged by springs to protrude outside of the housing; and an actuating member adapted to keep the main latch protruded out of the housing and operable with a push plate to release the main latch from being kept protruded. The auxiliary latch has a side projection which stops the actuating member at a first position where the auxiliary latch is protruded and the tongue is so disposed to be accommodated by an inner recess of the main latch such that the main latch is free to retract from the protruded position; the same side projection also stops the actuating member at a second position where the auxiliary latch is retracted and the main latch is protruded.