1. A positioning method for positioning a present position of a terminal device including a central processing unit (CPU), the positioning method comprising: (a) executing by the CPU a cumulative addition of I components of a received positioning signal from a satellite and a cumulative addition of Q components of the received positioning signal for either one of the polarities, the received positioning signal being spread-modulated with a spread code that can be reversed in polarity by navigation data; (b) calculating by the CPU sum of squares of the result of the cumulative addition of I components and the result of the cumulative addition of Q components in step (a); (c) calculating by the CPU correlation between the sum of squares calculated in step (b) with a replica code of the spread code; and (d) executing by the CPU a positioning calculation of the present position based on the result of the correlation calculation in step (c) to inform a user the present position.