Door opening and closing mechanism

A door opening and closing mechanism having a support part supporting a door to a main body and a guide part for guiding movement of the door during opening and closing, of the door the guide part comprising a guide rail provided inside of the main body and beneath a floor plate of the main body along an outer side surface of the main body and a rail support which moves along the guide rail while being coupled to one end of the door through a pivotal joint and guides the one end of the door along the outer side surface of the main body during the opening and closing, of the door and the support part comprising two links which align with each other to approximately form a line when the door is one of opened and closed, one link of said two links being connected at one end thereof to the door through a plurality of pivotal joints which are separated from each other in a vertical direction, the other link being connected at one end thereof to the main body through a plurality of pivotal joints which are separated from each other in the vertical direction and being connected at an opposite end thereof to the one link through a plurality of pivotal joints which are separated from each other in the vertical direction, and a rod connecting the door and the main body for swinging the door away from the outer side surface of the main body and having a lengh which is shorter than the sum of the lengths of the one link and the other link, the rod regulating the movement of the other end of the door to travel along an arcuate path as the guide part guides the one end of the door.