Abstract: The estimator learning device contains an image acquisition unit that acquires stained images provided by photographing respectively in a plurality of wavebands a biomaterial sample that has been stained with a prescribed staining solution; a cell nucleus extraction unit that extracts a cell nucleus region present in the biomaterial sample in each of the stained images; a color information acquisition unit that calculates, for each of the stained images, an absorbance in each of the wavebands in the cell nucleus region; and an estimator learning unit that, based on a relationship between the absorbance in each of the wavebands and information associated with the biomaterial sample and relating to whether the cell nucleus present in the biomaterial sample is in a prescribed state, trains an estimator that estimates whether the cell nucleus is in the prescribed state from the absorbance in each of the wavebands.