A respiratory induction apparatus for inducing respiration of a patient in particle beam therapy, comprising: a desired respiratory signal generation unit that is configured to generate a desired respiratory signal (R tj (t)) for inducing respiration of the patient; a real respiration measurement unit that is configured to measure real respiration of the patient and to output a real respiratory signal (R rl (t)) obtained through the measurement; a respiratory induction control unit configured to control whether or not particle-beam irradiation onto a patient should be implemented; a respiratory information instruction apparatus having a display and a speaker; a respiration evaluation unit which comprises a respiration evaluation information calculation unit (7cE1), a respiratory state evaluation unit (7cE2) that is configured to evaluate a misalignment of the real respiration from the desired respiratory signal (R tj (t)) and a navigation modification information generating unit (7cE3) that is configured to generate a modification information (I md) which is outputted to the respiratory induction control unit and to the respiratory information instruction apparatus; and characterized in that the respiration evaluation information calculation unit (7cE1) is configured to calculate, utilizing data of a single period (T res) of the desired respiratory signal (R tj (t)), a pair of coefficients (a 1, b 1), of trigonometric functions, which correspond to the 1st-order terms at a time when Fourier series expansion is applied to data of the desired respiratory signal (R tj (t)) and data of the real respiratory signal (R rl (t)), which is acquired in synchronization with the data of the desired respiratory signal (R tj (t)), and to perform comparisons between the respective gains (G tj, G rl) and between the respective phases (φ tj, φ rl), which are obtained from the calculated coefficients (a 1, b 1), so that there is evaluated a misalignment of the real respiration from the desired respiratory signal (R tj (t)); and in that the navigation modification information generating unit (7cE3) is configured to generate specific instruction for modifying the phase of the respiratory signal to be advanced or delayed and the gain to be deeper or more shallow, based on the evaluation results by the respiration evaluation unit (7cE2). a desired respiratory signal generation unit that is configured to generate a desired respiratory signal (R tj (t)) for inducing respiration of the patient; a real respiration measurement unit that is configured to measure real respiration of the patient and to output a real respiratory signal (R rl (t)) obtained through the measurement; a respiratory induction control unit configured to control whether or not particle-beam irradiation onto a patient should be implemented; a respiratory information instruction apparatus having a display and a speaker; a respiration evaluation unit which comprises a respiration evaluation information calculation unit (7cE1), a respiratory state evaluation unit (7cE2) that is configured to evaluate a misalignment of the real respiration from the desired respiratory signal (R tj (t)) and a navigation modification information generating unit (7cE3) that is configured to generate a modification information (I md) which is outputted to the respiratory induction control unit and to the respiratory information instruction apparatus; and characterized in that the respiration evaluation information calculation unit (7cE1) is configured to calculate, utilizing data of a single period (T res) of the desired respiratory signal (R tj (t)), a pair of coefficients (a 1, b 1), of trigonometric functions, which correspond to the 1st-order terms at a time when Fourier series expansion is applied to data of the desired respiratory signal (R tj (t)) and data of the real respiratory signal (R rl (t)), which is acquired in synchronization with the data of the desired respiratory signal (R tj (t)), and to perform comparisons between the respective gains (G tj, G rl) and between the respective phases (φ tj, φ rl), which are obtained from the calculated coefficients (a 1, b 1), so that there is evaluated a misalignment of the real respiration from the desired respiratory signal (R tj (t)); and in that the navigation modification information generating unit (7cE3) is configured to generate specific instruction for modifying the phase of the respiratory signal to be advanced or delayed and the gain to be deeper or more shallow, based on the evaluation results by the respiration evaluation unit (7cE2).