A packaging body configured to house a liquid injection device, the liquid injection device comprising a syringe that has a barrel part capable of being filled with a liquid and a needle attached to a distal portion of the barrel part for discharging the liquid, a cap that covers the needle, and a housing that covers at least a base end part of the syringe, the liquid injection device having a step part (725, 726) that is formed on an outer peripheral surface of the cap or between the housing and the cap, which the step part (725, 726) protrudes further outward than the side surface of the barrel part, the packaging body comprising: a container comprising a housing space configured to house the liquid injection device, and an opening configured to remove the liquid injection device from the housing space, the container being configured to be attached to a sealing member configured to seal the opening, and wherein the container comprises an engaging part that is configured to engage with the step part (725, 726) so as to remove the cap from the liquid injection device,wherein the container has a bottom part, side wall parts that extend upward from the surrounding of the bottom part, the opening surrounded by upper ends of the side wall parts, and a flange part that laterally extends from the upper ends of the side wall parts and is configured to be attached to the sealing member, characterized in that a notch part is provided at a part of the flange part, the notch part opening toward laterally, and a lower end surface of the notch part functions as the engaging part. the liquid injection device comprising a syringe that has a barrel part capable of being filled with a liquid and a needle attached to a distal portion of the barrel part for discharging the liquid, a cap that covers the needle, and a housing that covers at least a base end part of the syringe, the liquid injection device having a step part (725, 726) that is formed on an outer peripheral surface of the cap or between the housing and the cap, which the step part (725, 726) protrudes further outward than the side surface of the barrel part, the packaging body comprising: a container comprising a housing space configured to house the liquid injection device, and an opening configured to remove the liquid injection device from the housing space, the container being configured to be attached to a sealing member configured to seal the opening, and wherein the container comprises an engaging part that is configured to engage with the step part (725, 726) so as to remove the cap from the liquid injection device,wherein the container has a bottom part, side wall parts that extend upward from the surrounding of the bottom part, the opening surrounded by upper ends of the side wall parts, and a flange part that laterally extends from the upper ends of the side wall parts and is configured to be attached to the sealing member, characterized in that a notch part is provided at a part of the flange part, the notch part opening toward laterally, and a lower end surface of the notch part functions as the engaging part. a container comprising a housing space configured to house the liquid injection device, and an opening configured to remove the liquid injection device from the housing space, the container being configured to be attached to a sealing member configured to seal the opening, and wherein the container comprises an engaging part that is configured to engage with the step part (725, 726) so as to remove the cap from the liquid injection device,wherein the container has a bottom part, side wall parts that extend upward from the surrounding of the bottom part, the opening surrounded by upper ends of the side wall parts, and a flange part that laterally extends from the upper ends of the side wall parts and is configured to be attached to the sealing member, characterized in that a notch part is provided at a part of the flange part, the notch part opening toward laterally, and a lower end surface of the notch part functions as the engaging part.