To provide a door opening and closing mechanism capable of eliminating user's feeling of anxiety.

This door opening and closing mechanism for selectively opening and closing a door 41 covering an opening portion of a device main body 40 from one side while applying both end portions opposite to each other, as pivot shafts 44, comprises a link mechanism 50 having a link 51 for connecting the door 41 and the device main body 40 at a position separating from pivot shafts 44 of both ends and moving forward and backward in accordance with the opening and closing of the door 41, and the link mechanism 50 comprises first and second connecting portions 52, 53 rotatably disposed on both ends of the link 51, a first guide portion 54 disposed on the door 41 and supporting the first connecting portion 52 slidably in the direction connecting both end portions of the door 41, and a second guide portion 55 disposed on the device main body 40 and supporting the second connecting portion 53 slidably in the direction vertical to an opening face of the opening portion.