Provided are a method for preparing a thin film or a thick film, including: a first step of providing a porous substrate capable of supplying silicon; a second step of applying zeolite seed crystals onto the surface of the porous substrate; a third step of coating the seed crystals-applied porous substrate with an aqueous solution containing a structure-directing agent; and a fourth step of forming and growing a film from the seed crystals by the secondary growth above a temperature at which moisture inside the seed crystals-applied porous substrate prepared in the third step can form steam, and a film prepared by the method. The film manufacturing method of the present invention is a simple manufacturing process, and thus has high reproducibility and high throughput. Since a synthetic gel is not used and a solution is used, the unnecessary consumption of materials, environmental pollution, and waste of a synthetic gel can be prevented while not necessitating drying and washing of a film.