PURPOSE: To allow a handle to return to an original position upon release thereof by providing a spring cassette to a lockset wherein a latch bolt appears/ disappears when a handle lever is rotated, and to allow easy operation and fitting by adjusting a liner position according to the thickness of door.

CONSTITUTION: Spring cassettes 38 and 50 are provided to a cylindrical lockset 30 wherein rotation of hand levers 42 and 54 provided on front and rear surfaces of a door allows appearance/disappearance of a latch bolt 60, so the handles 42 and 54 return to the original position upon release thereof. A housing 74 for housing the latch bolt 60 is fitted through screw sleeves 76 and 78, and the position of liners 36 and 48 is fitted through adjustment according to the thickness of door. Thus, a lockset is provided wherein opening/closing of a door is easy and fitting/adjusting is also easy.