A degradation estimation method performed by a degradation estimation apparatus connected to a device and a maintenance service via networks, comprising the steps of: receiving first device data from a sensor installed in the device, the first device data indicating a state of the device; sending a first alarm, when estimating that there is a degradation using a first determination standard, wherein the first determination standard was determined in advance for estimating whether there is degradation of the device or not; characterized by: acquiring a service record of maintenance of the device indicating details of a maintenance of the device performed in response to the first alarm; analyzing a degradation state of the device from the service record, wherein presence or absence of degradation of the device is determined from the service record; adjusting the first determination standard to a second determination standard depending on the degradation state analyzed; when determined that there is no degradation of the device, the second determination standard is set higher than the first determination standard; receiving second device data from the sensor indicating a state of the device; estimating whether there is degradation of the device or not using the second device data received and the second determination standard; sending a second alarm, when estimating that there is a degradation using the received second device data and the second determination standard; in the estimating, the device is estimated as having degradation when a first degradation index is greater than the second determination standard, the first degradation index being calculated based on the first device data; and in the adjusting, when it is estimated from the service record that no service is performed, the second determination standard is set higher than a maximum value of a third degradation index, the maximum value of the third degradation index being calculated from third device data indicating a state of the device in a predetermined period up to time the maintenance is performed. receiving first device data from a sensor installed in the device, the first device data indicating a state of the device; sending a first alarm, when estimating that there is a degradation using a first determination standard, wherein the first determination standard was determined in advance for estimating whether there is degradation of the device or not; characterized by: acquiring a service record of maintenance of the device indicating details of a maintenance of the device performed in response to the first alarm; analyzing a degradation state of the device from the service record, wherein presence or absence of degradation of the device is determined from the service record; adjusting the first determination standard to a second determination standard depending on the degradation state analyzed; when determined that there is no degradation of the device, the second determination standard is set higher than the first determination standard; receiving second device data from the sensor indicating a state of the device; estimating whether there is degradation of the device or not using the second device data received and the second determination standard; sending a second alarm, when estimating that there is a degradation using the received second device data and the second determination standard; in the estimating, the device is estimated as having degradation when a first degradation index is greater than the second determination standard, the first degradation index being calculated based on the first device data; and in the adjusting, when it is estimated from the service record that no service is performed, the second determination standard is set higher than a maximum value of a third degradation index, the maximum value of the third degradation index being calculated from third device data indicating a state of the device in a predetermined period up to time the maintenance is performed. acquiring a service record of maintenance of the device indicating details of a maintenance of the device performed in response to the first alarm; analyzing a degradation state of the device from the service record, wherein presence or absence of degradation of the device is determined from the service record; adjusting the first determination standard to a second determination standard depending on the degradation state analyzed; when determined that there is no degradation of the device, the second determination standard is set higher than the first determination standard; receiving second device data from the sensor indicating a state of the device; estimating whether there is degradation of the device or not using the second device data received and the second determination standard; sending a second alarm, when estimating that there is a degradation using the received second device data and the second determination standard; in the estimating, the device is estimated as having degradation when a first degradation index is greater than the second determination standard, the first degradation index being calculated based on the first device data; and in the adjusting, when it is estimated from the service record that no service is performed, the second determination standard is set higher than a maximum value of a third degradation index, the maximum value of the third degradation index being calculated from third device data indicating a state of the device in a predetermined period up to time the maintenance is performed.