To calculate a positional shift between the design position and the fixing position of a sheet sensor and to employ control the calculated value as a correction value in the control of a sheet.

A print head fixed to a carriage and first and second sheet sensors are set at reference positions and then moved by a third distance therefrom before starting print operation through a print head. Print is detected by the first and second sheet sensors and the positional shift thereof is determined based on a design value, i.e., a first or second distance, a detection value, i.e., a third or fourth distance, and a print detected by the first or second sheet sensor.