To provide a sheet-like workpiece attitude detecting method and device capable of exactly detecting rotary attitude change amount of a sheet-like workpiece.

This detecting device is provided with two pairs of four sensors A1 and A2 and B1 and B2 arranged at prescribed intervals on conveying lines r1 and r2 of the sheet-like workpiece (n) to detect the sheet-like workpiece (n), and an arithmetic circuit (en) for performing an arithmetic processing for a detection signal outputted from each sensor A1 and A2 and B1 and B2. Each two sensors of the two pairs of four sensors A1 and A2 and B1 and B2 are arranged at prescribed intervals at positions orthogonal to a rotary shaft (fa) of a feed roller F for delivering the sheet-like workpiece (n) to the front on the inlet side and outlet side of the feed roller F, respectively. The arithmetic processing is performed for a difference t of a time difference t1 detected by the two sensors A1 and B1 arranged on the inlet side of the feed roller F and a time difference t2 detected by the two sensors A2 and B2 arranged on the outlet side of the feed roller F in the arithmetic circuit (en).