Emerging magnetic flux tubes in the solar convection zone are thought to be responsible for formation of active regions. We performed two-dimensional MHD simulations of the flux emergence from the solar interior to the atmosphere. The flux tube is initially placed deep down at the convection zone (-20,000km) and perturbed to generate Parker instability. The tube rises through the convection zone, but stops below the surface bacause of the strong pressure gradient. After being unstable to the Parker instability, the tube emerges to the atmosphere again. We show this 'two-step emergence' model and have some discussions on the parameter survey.