A method for managing loading of a paper feed cassette in an image forming apparatus, comprising steps of:
- forming an image;
- accommodating a paper on which the image is to be formed in a paper feed cassette;
- inputting an instruction for changing the size of the paper in conjunction with the paper feed cassette from an operation panel;
- loading/unloading the paper feed cassette on/from a cassette loading section;
- outputting from a sensor a signal indicative of loading/unloading of the paper feed cassette on/from the cassette loading section;
- and
- determining that the paper size change has been done appropriately by determining that the paper feed cassette accommodating the size of paper to be changed has been loaded within a first predetermined time period immediately before the instruction is inputted or within a second predetermined time period immediately after the instruction is inputted, and that an unloaded period of the cassette loading section is more than a third predetermined period.