The invention concerns a height adjustment device (1) for a handle (4) of a rollator, comprising: —an inner tube (2) telescopically received in an outer tube (3), the handle (4) of the rollator being connected at the upper end of said inner tube (2), —a locking assembly (10) adapted to lock the inner tube (2) in a fixed position with regard to the outer tube (3), —an unlocking assembly (20) adapted to unlock the inner tube (2) from said fixed position.