A retractable door structure for a storage case including a pair of guide grooves formed from the front end to the back end of the inner surfaces of the case panel, sliding blocks connected to each other by a connecting rod provided in the guide grooves, and a pinion mounted in each of the sliding blocks which is designed to engage with a rack formed in the guide grooves. The door is pivotally held between the sliding blocks by rotary shafts attached to the corners of the door. By means of this structure, the door can be slid inside the case after it is opened and the door is easily pushed in and pulled out of the case since the sliding blocks holding the door slide smoothly in the guide grooves.