Immunochromatographic assay apparatus

An immunochromatographic assay apparatus comprising:

• a loading part in which a cartridge including an assay strip having an assay region of which a density varies depending on an amount of a test substance included in a sample is attachably and detachably loaded;
• a detection unit that detects the density of the assay region;
• and
• a processor configured to perform a positive-negative determination of whether the sample is positive or negative based on the density acquired from the detection unit,
• wherein the processor is configured to
• start acquisition of the density from the detection unit from a preset time point before the density is saturated, and
• perform saturation point determination of whether or not the density has reached a saturation point based on a time change of the density, and in a case where it is determined in the saturation point determination that the density has reached the saturation point, perform the positive-negative determination.