The present invention relates to a data conversion apparatus and a learning device in which an image can be converted into a higher-quality image. A class-tap generating circuit (2) and a predictive-tap generating circuit (3) generate, from an SD image, a predictive tap used for determining the HD pixel of a specified block of an HD image. A classification circuit (4) classifies the HD pixel of the specified block based on the class tap. A coefficient RAM (7) obtains a tap coefficient for the class of the HD pixel of the specified block from tap coefficients obtained by learning the relationship between supervisor data and learner data for each class of at least one class by giving a predetermined constraint condition to the supervisor data. A predictive-computation circuit (8) and a decoding circuit (9) determine the HD pixel of the specified block by using the tap coefficient and the predictive tap.