To provide a sheet transfer device and an image reading device convenient at maintenance or the like.

The sheet transfer device for transferring a sheet includes: a device body formed by connecting a first unit to a second unit so as to be openable and closable; a sheet transfer path formed between the first unit in a closed state and the second unit to extend from above the device body in the downward direction; and a sheet transfer means disposed on the sheet transfer path to nip and transfer the sheet by a pair of rollers disposed to face each other across the sheet transfer path. The second unit comprising a release means which is disposed at the upper end of the second unit, and release the nipping force of the pair of rollers by being pushed down toward the lower end of the device body. When the nipping force is released by the release means, the first unit is brought into an opened state that the first unit separates from the second unit.