The invention provides a sheet determination apparatus characterised in that: a thickness sensor with a plurality of thickness detection elements arranged over an entire width of a transport passage for detecting a thickness of sheets, which pass the transport passage, is provided, profile data representative of sheets is extracted from detection waveform detected by every thickness detection element, the number of sheets is determined by comparing and judging the extracted profile data with profile basic data as a reference stored in a storage means. Thereby, even in abnormal transport states such as overlaying transport, slope transport or the like, and in transport process of the sheets in which the transported sheets having various states of bending, breakage, damage and the like, the number and type of sheets can be accurately determined, hence, a high reliable sheet determination apparatus can be realized.