A robot controller includes a first time-series data obtaining part for obtaining first data used for fault diagnosis in time series and store the first data as first time-series data, a second time-series data obtaining part for obtaining second data used for extraction of the first data which is used for the fault diagnosis in time series and store the second data as second time-series data, a time specification part for specifying extraction time of the first data used for the fault diagnosis based on the second time-series data, a data extraction part for extracting the first data corresponding to the extraction time, and a diagnosis performing part for performing the fault diagnosis of the robot based on the first data extracted by the data extraction part.