A slide package comprising: a rectangular box-shaped outer box having an opening at one end thereof; and a rectangular box-shaped inner box accommodated in the outer box and slidable outward from the opening, the inner box having a wall section closing the opening of the outer box, wherein: the outer box includes an inner flap extending inward in a sliding direction of the inner box along an inner surface of the outer box, the inner box includes a box body, a lid section connected to a rear end of the box body and pivotable back and forth in a direction perpendicular to the sliding direction of the inner box, the lid section including the wall section, and a lid opening device including an engaging member extending from a rear part of the lid section inward in the sliding direction of the inner box, the lid opening device allowing the inner flap to engage with the engaging member and pull the rear part of the lid section to cause the lid section to pivot rearward when the inner box is slid outward, and part of the inner box is exposed when the inner box is slid outward from the opening, to open a front side of the slide package which is one side surface of the exposed part and is located opposite the rear end, characterized in that the engaging member has an open hole with which the inner flap engages, and a protrusion projecting rearward from the inner box toward the outer box, the inner flap has an engaging hole with which the protrusion can be engaged, and the protrusion is pivotable in the sliding direction of the inner box relative to the engaging member and is configured such that the protrusion is inserted into and engaged with the engaging hole with a distal end of the protrusion directed outward and urges the lid section of the inner box frontward with the distal end in contact with the outer box while the inner box is accommodated in the outer box with the opening closed with the wall section, and disengages from the engaging hole with the distal end reversed from an outward orientation to an inward orientation when the inner box is slid outward. the outer box includes an inner flap extending inward in a sliding direction of the inner box along an inner surface of the outer box, the inner box includes a box body, a lid section connected to a rear end of the box body and pivotable back and forth in a direction perpendicular to the sliding direction of the inner box, the lid section including the wall section, and a lid opening device including an engaging member extending from a rear part of the lid section inward in the sliding direction of the inner box, the lid opening device allowing the inner flap to engage with the engaging member and pull the rear part of the lid section to cause the lid section to pivot rearward when the inner box is slid outward, and part of the inner box is exposed when the inner box is slid outward from the opening, to open a front side of the slide package which is one side surface of the exposed part and is located opposite the rear end, characterized in that the engaging member has an open hole with which the inner flap engages, and a protrusion projecting rearward from the inner box toward the outer box, the inner flap has an engaging hole with which the protrusion can be engaged, and the protrusion is pivotable in the sliding direction of the inner box relative to the engaging member and is configured such that the protrusion is inserted into and engaged with the engaging hole with a distal end of the protrusion directed outward and urges the lid section of the inner box frontward with the distal end in contact with the outer box while the inner box is accommodated in the outer box with the opening closed with the wall section, and disengages from the engaging hole with the distal end reversed from an outward orientation to an inward orientation when the inner box is slid outward.