Using flat cylindrical samples having non-uniform dielectric properties, we studied the heat transfer in food products when only the side surfaces of the samples were irradiated with microwaves. The temperature distributions in the food were measured by means of an infrared thermometer in two-dimensional form. Additionally, a transient two-dimensional heat conduction equation was induced and the temperature distributions in the food were determined using a numerical calculation. When the experimental results were compared with the results of the numerical calculations, their tendency of temperature distribution closely agreed, and it was confirmed that the mathematical model is useful in predicting the temperature distributions of food with non-uniform dielectric properties during microwave heating.