A chaos spreading code c(n) is inputted to a spreading unit 32. Data D1
and c(n) are multiplied in the spreading unit 32. A chaos spreading code
d(n) is inputted to a spreading unit 42. Data D2 and d(n) are multiplied
in the spreading unit 42. The chaos spreading codes c(n) and d(n)
orthogonally cross each other. Outputs of the spreading units 32 and 42
are added by an adder 35 and transmitted through a transmitting unit 36
to a transmission path 38. By making an initial value which is set in a
chaos sequence generator having a construction of a digital circuit
different, the chaos spreading codes which orthogonally cross can be
formed. Since the chaos spreading codes c(n) and d(n) orthogonally cross,
an orthogonal modulating unit having a construction of an analog circuit
for amplitude-modulating carriers which orthogonally cross can be made
unnecessary and the construction can be simplified.