There is provided a collapsible ladder having several collapsible ladder sections, where each or at least part of the ladder sections comprises two hollow ladder bars arranged parallel to each other and interconnected at an upper end by a rung, and where each collapsible ladder section is telescopically inserted into a lower ladder section. Each ladder bar of a collapsible ladder section has a locking hole adjacent the lower end part of the ladder bar and an extension below the locking hole, and retaining mechanisms are provided in at least part of the rungs for locking the collapsible ladder sections relative to one another when the collapsible ladder sections are extended. Each of or part of the retaining mechanisms comprises a locking pin, which can be brought into an extended and locked position in order to engage a corresponding locking hole provided in the ladder bar of a ladder section positioned there above, and a release part for bringing the locking pin into a retracted and un-locked position. At least part of the rungs holding a retaining mechanism with a locking pin and a release part have spacers provided at the bottom, where at least part of said spacers have a release actuator with a bottom part extending below the spacer when the ladder section above the rung is locked in the extended position. The release actuator engages the release part of a retaining mechanism of the rung and is arranged to activate the release part when the bottom part of the release actuator is moved upwards through the spacer thereby bringing the locking pin into the un-locked position.