An image processing apparatus of the present invention performs reconstruction processing on a projected image of an object obtained by using a radiation source and a detector in order to obtain a tomographic image in which noise has been reduced regardless of the type of reconstruction filter that is used. The image processing apparatus includes a selection means that selects a reconstruction filter in accordance with an imaging technique; a setting means that sets an image processing parameter for noise reduction according to the type of the selected reconstruction filter; an image processing means that performs image processing on the projected image using the image processing parameter; and a reconstruction means that uses the selected reconstruction filter to perform reconstruction processing on the projected image resulting from the image processing and obtain a tomographic image of the object.