A device with lock function includes a housing, a casing and a lock mechanism. The housing has a first engaging portion. The lock mechanism includes a frame, a lock member, a first elastic member, an operating member and an unlock member. The frame has a second engaging portion. The lock member has a third engaging portion engaging with the first engaging portion to lock the casing in the housing. The unlock member has a fourth engaging portion engaging with the second engaging portion to restrain the operating member. When the unlock member is pressed, the fourth engaging portion disengages from the second engaging portion and the first elastic member drives the lock member to move toward an inside of the frame, such that the third engaging portion disengages from the first engaging portion and the lock member drives the operating member to move toward an outside of the frame.