1. A sensor evaluation system coupled to a network including a plurality of sensors and an analysis system having a service execution part for providing analysis service using time series sensor data obtained from at least one of the plurality of sensors, comprising: a time series data recorder in which time series data showing changes with time of events having predetermined relations with the analysis service is recorded by associating with the analysis system; a sensor relevance ratio calculator calculating sensor relevance ratios indicating relevance ratios of sensor data to the time series data by comparing changes with time of events indicated by the time series data and time series records of the sensor data used by the service execution part to provide analysis service in an identical period; and a sensor importance calculator calculating sensor importance using the sensor relevance ratios calculated by the sensor relevance ratio calculator wherein the sensor relevance ratio calculator performing regression analysis using changes with time of events indicated by the time series data and time series records of the sensor data used by the service execution part to provide analysis service and calculates sensor relevance ratios based on results of performing the regression analysis.