A container for retort food, the container comprising: a container body; and an inner cap; wherein the container body comprises a container bowl part having a space which is recessed with a first depth in a downward direction and open in an upward direction and a container flange part constituting a periphery of an upper end of the container bowl part; wherein the inner cap comprises a cap tray part having a space which is recessed with a second depth in the downward direction and open in the upward direction and a cap flange part constituting a periphery of an upper end of the cap tray part, wherein, when the inner cap is placed on the container body, the cap tray part is located inside an upper region of an inner space of the container bowl part of the container body, and the cap tray part divides the inner space of the container bowl part into upper and lower spaces, wherein, when thermal fusion is performed in a state in which the cap flange part is placed on the container flange part, the lower space inside the container bowl part is sealed, wherein the cap tray part has a three-dimensional rib structure on a bottom surface thereof; characterized in that the three-dimensional rib structure comprises: a first rib which is made of protrusions and recesses repeatedly formed along a circumferential region on the bottom surface of the cap tray part; and a second rib which is formed on the bottom surface of the cap tray part and has a ring shape having a predetermined inner diameter and of which a cross-section has a shape having predetermined curvature. a container body; and an inner cap; wherein the container body comprises a container bowl part having a space which is recessed with a first depth in a downward direction and open in an upward direction and a container flange part constituting a periphery of an upper end of the container bowl part; wherein the inner cap comprises a cap tray part having a space which is recessed with a second depth in the downward direction and open in the upward direction and a cap flange part constituting a periphery of an upper end of the cap tray part, wherein, when the inner cap is placed on the container body, the cap tray part is located inside an upper region of an inner space of the container bowl part of the container body, and the cap tray part divides the inner space of the container bowl part into upper and lower spaces, wherein, when thermal fusion is performed in a state in which the cap flange part is placed on the container flange part, the lower space inside the container bowl part is sealed, wherein the cap tray part has a three-dimensional rib structure on a bottom surface thereof; characterized in that the three-dimensional rib structure comprises: a first rib which is made of protrusions and recesses repeatedly formed along a circumferential region on the bottom surface of the cap tray part; and a second rib which is formed on the bottom surface of the cap tray part and has a ring shape having a predetermined inner diameter and of which a cross-section has a shape having predetermined curvature. a first rib which is made of protrusions and recesses repeatedly formed along a circumferential region on the bottom surface of the cap tray part; and a second rib which is formed on the bottom surface of the cap tray part and has a ring shape having a predetermined inner diameter and of which a cross-section has a shape having predetermined curvature.