A monitoring apparatus comprising a processing circuit, wherein the processing circuit is configured to acquire measurement values of sensors installed in a system (S201), acquire a control signal from the system (S202), acquire a model that is configured to generate second data including a prediction value of each of sensors belonging to a second sensor set including, as an element, a second sensor correlated with a first sensor when first data is input, the first data including a measurement value of each of sensors belonging to a first sensor set including, as an element, the first sensor of which a measurement value changes in conjunction with a change in the control signal in a case where the control signal changes greatly in a short period and then returns to an original state during a predetermined operation mode (S203), generate a determination signal by determining a change in the control signal (S204), generate the second data including a prediction value of each of the sensors belonging to the second sensor set from the first data and the model, the first data including, of the measurement values acquired from the system, the measurement value of each of sensors belonging to the first sensor set (S205), and detect an anomaly of the system or an anomaly of at least one sensor belonging to the second sensor set based on a measurement value of each of the sensors belonging to the second sensor set, the second data, the determination signal, and a threshold (S207), wherein the processing circuit is configured to make it difficult to detect the anomaly in a case where the determination signal indicates that there is a change in the control signal by increasing an upper threshold and reducing a lower threshold for the difference between the measurement value and the prediction value of the at least one sensor used for detecting the anomaly during the predetermined operation mode (S303). the processing circuit is configured to acquire measurement values of sensors installed in a system (S201), acquire a control signal from the system (S202), acquire a model that is configured to generate second data including a prediction value of each of sensors belonging to a second sensor set including, as an element, a second sensor correlated with a first sensor when first data is input, the first data including a measurement value of each of sensors belonging to a first sensor set including, as an element, the first sensor of which a measurement value changes in conjunction with a change in the control signal in a case where the control signal changes greatly in a short period and then returns to an original state during a predetermined operation mode (S203), generate a determination signal by determining a change in the control signal (S204), generate the second data including a prediction value of each of the sensors belonging to the second sensor set from the first data and the model, the first data including, of the measurement values acquired from the system, the measurement value of each of sensors belonging to the first sensor set (S205), and detect an anomaly of the system or an anomaly of at least one sensor belonging to the second sensor set based on a measurement value of each of the sensors belonging to the second sensor set, the second data, the determination signal, and a threshold (S207), wherein the processing circuit is configured to make it difficult to detect the anomaly in a case where the determination signal indicates that there is a change in the control signal by increasing an upper threshold and reducing a lower threshold for the difference between the measurement value and the prediction value of the at least one sensor used for detecting the anomaly during the predetermined operation mode (S303). <EOS>