To smooth the movement of a cover plate of an emergency cylinder lock of an electric lock and to stabilize the attached state of the cover plate.

A slide cover has a pair of guide grooves 12, 12 provided on a cover plate; a pair of slide pins 11, 11 to slidably engage in the guide groove 12; and a pair of protrusive stripes 14, 14 which extend inside the guide groove 12 and are elastically supported. The guide groove is formed in an about L- shape by serially arranging the first guide groove 12a for leading the slide pin 11 so that the cover plate 4 may move vertically in a state of the cover plate 4 separated from a base plate and the second guide groove 12b for leading the slide pin so that the cover plate 4 may be seated at a normal attaching position at one end of the first guide groove 12a. A locking recessed stripe 17 to engage with the protrusive stripe 14 in a state of the cover plate seated at a normal attaching position is formed on a connecting plate 9 protrusively provided on the inside of the cover plate 4.