There is provided a gamma curve adjustment device used to adjust the gamma curve indicating the relationship of input tone values to output tone values for use in a gamma correction circuit that performs gamma correction of an image signal. The gamma curve adjustment device includes a user interface module that permits a user to specify desired output tone values for a plurality of pre-established adjustment points on the gamma curve, and an adjustment module that adjusts the gamma curve such that the output tone value at each adjustment point assumes the value specified through the user interface module. The plurality of adjustment points are established such that a differential of input tone values between a first set of two adjustment points situated adjacently on the gamma curve differs from a differential of input tone values between a second set of two adjustment points situated adjacently on the gamma curve.