To provide a movable partition wall easily fixable in a desired position, and also to provide an installation structure of the movable partition wall.

This movable partition wall is provided with: a partition wall body 5; a slider 6 attached to the upper end of the partition wall body 5; a movable body 7 attached to the lower end of the partition wall body 5; first elastic members 8 attached to the upper end of the partition wall body 5; and second elastic members 9 inserted between the lower end of the partition wall body 5 and a floor 2. The partition wall body 5 is secured to a ceiling 3 and the floor 2 by the frictional force caused between the first elastic members 8 and the ceiling 3 and the frictional force caused between the second elastic members 9 and the floor 2 in the state of being sandwiched by the first elastic members 8 and the second elastic members 9. The movable partition wall 1 is thereby easily secured in a desired position after being freely moved horizontally along a rail 15.