Slot device for immobilizer authentication system

A slot device (1) for an immobilizer authentication system, includes: a movable holder (3) which has a storage portion (3b) into which a mobile unit (10) can be removably inserted and is able to move in a sliding manner; a return spring for returning the movable holder to an initial position; a detection switch (6); and a lock mechanism capable of gripping the movable holder (3) at a predetermined sliding position; and by pressing the mobile unit (10) inserted into the storage portion (3b) and held by the movable holder (3) in the inserting direction against a pressing force of the return spring, wherein the slot device (1) includes an operating slider (5) having a portion to be pressed (5c) which is disposed at a part inside of the storage portion (3b) and an operating portion (5a) which extends from the portion to be pressed (5c) and protrudes to outside of the movable holder (3); and the operating portion (5a) makes the detection switch (6) turn on by making the portion to be pressed (5c) be pressed by the mobile unit (10).