A substrate storing container includes: a container body for storing semiconductor wafers; a door that is fitted to the front of the container body; and a locking mechanism locking the door. The locking mechanism includes: a rotary driver that is supported by the door and operated from a cover plate side; and a locking bar that vertically slides as the rotary driver rotates to bring the distal end into, and out of, a locking hollow of the container body. The rotary driver is separated into first and second rotary drivers. The first and second rotary drivers are formed with first and second cam portions, respectively. The first and second cam portions are made to support the proximal end of the locking bar therebetween so that the locking bar can sway in the thickness direction of the door.