An image pickup apparatus includes a detector and an image processing unit. The detector executes image pickup operations in which electrical signals based on radiation are output and executes, in a period between a first image pickup operation and a second image pickup operation, a first inter-image pickup operation for suppressing a lag generated by the first image pickup operation and a second inter-image pickup operation for obtaining dark signals from the detector after the first inter-image pickup operation. The signal processing unit calculates a correction coefficient using a first time ts, a second time te, and the dark signals, predicts an amount of offset to be included in electrical signals of the second image pickup operation using a third time ts&prime, a fourth time te&prime, and the correction coefficient, and executes calculation using the electrical signals and the amount of offset output from the detector in the second image pickup operation.
