A data analyzer for analyzing characterization data to form fuel injection control, including a data obtainer that obtains data from a detection signal of a sensor as a time-series data that changes over time. The data analyzer further includes a differentiator that differentiates the time-series data obtained by the data obtainer, a moving averager that calculates a moving average of the differentiated time-series data by the differentiator, an identifier that identifies a waveform of the time-series data based on the moving average calculated by the moving averager, and a data characterizer characterizes the time-series data based on the waveform of the time-series data identified by the identifier. As such, noise is removed as much as possible, and characteristics of time-series data become analyzable.