Abstract: An image forming apparatus is provided. The image forming apparatus includes a reciprocal movement unit that reciprocally moves a carriage; a position sensor that detects a location of the carriage; a conveyance unit that conveys a recording medium in a sub-scan direction; an edge detection sensor that detects an edge of the recording medium; a both edge detection unit that detects positions of both edges of the recording medium from positions of the carriage when the edge detection sensor detects each edge of the recording medium; a detection start position determination unit that determines a detection start position; a print control unit that controls the recording head to record data on the recording medium; and a re-detection unit that moves the carriage to the detection start position during printing and that re-detects the edge of the recording medium from the detection start position using the edge detection sensor.