Provided are a fluctuation amount estimation device (9) capable of evaluating reliability of an estimated value and a correction amount calculation device (1) including the fluctuation amount estimation device (9). The correction amount calculation device (1) includes the fluctuation amount calculation device (9), a correction amount calculation unit (5), and a correction amount output unit (7). The fluctuation amount estimation device (9) includes a parameter storage (3) storing parameters as constituent elements of a neural network obtained by machine learning, an estimation unit (2) estimating a fluctuation amount relevant to a position of an element arranged in a machine tool (11) or a fluctuation amount of a distance between elements arranged in the machine tool (11) for each physical condition information of the machine tool (11) by means of the neural network with a parameter freely selected from the parameters being omitted, and a reliability evaluation unit (4) evaluating reliability of estimated multiple fluctuation amounts based on the estimated fluctuation amounts. The correction amount calculation unit (5) calculates a correction amount for the estimated fluctuation amounts based on the fluctuation amounts, and the correction amount output unit (7) outputs the calculated correction amount to outside.