A blood sugar level prediction device (10) is for predicting the blood sugar level of a user (30). The blood sugar level prediction device (10) is provided with a pattern selection unit (11) that selects one pattern from a plurality of preset blood sugar level time series variation patterns, based on the blood sugar level of the user (30) at the time of fasting, and a correction processing unit (12) that corrects the selected pattern using a plurality of measured values obtained by executing optical measurement of blood sugar levels over a number of measurement dates, targeting the user (30).