To solve the problem that it is necessary for a store clerk to insert and draw out a key to unlock a lock every time a displayed article is taken out from inside according to a request of a customer in a store as the lock member for crime prevention at night is continuously used in business hours of the store in a lock-type display device.

Only by stepping on a pedal 22 by a stepping operation when an displayed article is taken out from inside according to a request of a customer in business hours of a store, it is possible to speedily open a glass plate 6 as an opening/closing member. As the stepping operation of the pedal 22 is performed on the service side, it is advantageous for crime prevention from outside without damaging a satisfactory impression provided for the customer as the unlocking operation of the glass plate 6 is hidden from the customer.