A sheet storage device includes a sheet positioning member that is movable in a first direction, and positions a sheet by abutting on a side end portion of the sheet at a side in the first direction. The sheet positioning member includes a moving body, an abutting portion, a first and a second biasing member, and a bias removing portion. The moving body is configured to move in the first direction. The abutting portion is supported by the moving body to be movable in the first direction and configured to abut on the side end portion when the sheet positioning member positions the sheet. The first biasing member biases the abutting portion toward the side end portion. The second biasing member biases the abutting portion against a biasing force of the first biasing member. The bias removing portion removes a bias applied by the second biasing member.