A cassette conveyance apparatus (10) includes: a first conveyance means (20) for conveying a first cassette (40) in a horizontal and vertical direction; and a second conveyance means (30) for conveying a second cassette (50) in a horizontal and vertical direction . In the cassette conveyance apparatus (10), the first and second cassettes are circulated between a predetermined wafer accommodation position (P1), at which a wafer (2) is accommodated in the cassette, and a predetermined cassette replacement position (P0) at which a cassette accommodating a plurality of wafers is replaced with an empty cassette. Due to the foregoing, the wafers are continuously accommodated in the cassette without stopping an operation of a pretreatment step.