To provide a sheet storage device and an image forming device capable of properly storing a sheet, while making both compatible in feeding performance and skew performance.

A sheet storage part 15a is provided with a regulating means 2 regulating a position of an end part in the width direction of the sheet orthogonal to the inserting direction, and is also provided with a vertically rotatable intermediate plate 1 having a sheet loading part 1A positioned on the downstream side in the inserting direction more than the regulating means 2 and an arm member 4 freely rotatable as the rotational center 1a arranged on the upstream side in the inserting direction more than the regulating means 2. A downward extending cover part 13 is arranged in a regulating means side end part of the sheet loading part 1A of the intermediate plate 1. This cover part 13 blocks up a clearance generated between the sheet loading means 1A and the regulating means 2 when the sheet loading means 1A rotates upward on the downstream side in the inserting direction of the regulating means 2.