In a sheet feeding device, a document mounting board includes a first member that includes a first mounting surface and is located on the feed mechanism side in the feeding direction of the documents in the feed mechanism, the first mounting surface being inclined to a lower side toward the feed mechanism, and a second member that includes a second mounting surface on which the documents are mounted and is disposed on a side opposite to the side of the first member on which the feed mechanism is located, and the second member is connected to the first member to be rotatable about a second turning shaft and turns about the second turning shaft depending on the weight of the documents detected by the weight sensor to change an angle with respect to the first member.