A developing agent container includes: a container, a shutter that sets a supply hole to a closed state and an open state, a seal sponge that seals a gap between the first surface and the shutter when the supply hole is in the closed state, wherein the shutter has a first ridge line part that makes contact with the seal sponge due to the movement of the shutter, in a first edge part on a front end side in the first direction, the seal sponge has a second ridge line part that makes contact with the shutter due to the movement of the shutter in the first direction, in a second edge part on the opposite direction's side facing the supply hole, and the first ridge line part and the second ridge line part have a relationship in which one is inclined with respect to the other.