To solve such a problem that it is difficult to control the thickness of a second filter film by using an air bubble generating unit for hindering the filtering capacity of a filter from being deteriorated owing to, for example, the clogging of the second filter film formed on the surface of the filter.

According to an apparatus for removing an object to be removed from fluid and a method for removing the object to be removed using the apparatus, air diffusing pipes 26, 27, 28 are arranged at the bottom of an original water tank 1. Air of the same pressure is sent into each of air diffusing pipes 26, 27, 28 from both ends of each pipe, so that the quantities of air bubbles to be discharged from air diffusing pipes 26, 27, 28 are uniformized with one another. As a result, the second filter film 21 to be formed on the surface of the filter 4 can be adjusted and the filtering capacity of the filter can always be kept at a constant optimum value.