A baseband signal generating method using a baseband signal generation device, comprising: a pattern generating step of generating a scramble pattern; a multiplication value decision step of determining a positive or negative multiplication value corresponding to a bit value of each bit included in a binary bit string forming the scramble pattern generated in the pattern generating step; a symbol data generation step of receiving a supply of data whose significance level is predetermined, dividing significant bit data into one-bit data and adding a redundant bit to each of the one-bit data, and dividing less significant bit data into pieces of data each having a two bits, thereby generating pieces of two-bit symbol data each piece representing a 4-ary symbol including in a value area at least a pair of a positive value and a negative value having an identical absolute value; a multiplication processing step of performing multiplication between each piece of the symbol data generated in the symbol data generation step and the multiplication value determined in the multiplication value decision step; and a baseband signal generation step of generating a baseband signal 4-ary symbols based on the result of the multiplication in the multiplication processing step, the 4-ary symbols having in a value area at least a pair of positive value and negative value having an identical absolute value; wherein the redundant bit data in the symbol data generation step being determined such that, in the baseband signal, a minimum value of a difference between momentary values of two points representing two symbols including the redundant bit data and having different values is larger than a minimum value of a difference between momentary values of two points representing two symbols including no redundant bit data and having different values. a pattern generating step of generating a scramble pattern; a multiplication value decision step of determining a positive or negative multiplication value corresponding to a bit value of each bit included in a binary bit string forming the scramble pattern generated in the pattern generating step; a symbol data generation step of receiving a supply of data whose significance level is predetermined, dividing significant bit data into one-bit data and adding a redundant bit to each of the one-bit data, and dividing less significant bit data into pieces of data each having a two bits, thereby generating pieces of two-bit symbol data each piece representing a 4-ary symbol including in a value area at least a pair of a positive value and a negative value having an identical absolute value; a multiplication processing step of performing multiplication between each piece of the symbol data generated in the symbol data generation step and the multiplication value determined in the multiplication value decision step; and a baseband signal generation step of generating a baseband signal 4-ary symbols based on the result of the multiplication in the multiplication processing step, the 4-ary symbols having in a value area at least a pair of positive value and negative value having an identical absolute value; wherein the redundant bit data in the symbol data generation step being determined such that, in the baseband signal, a minimum value of a difference between momentary values of two points representing two symbols including the redundant bit data and having different values is larger than a minimum value of a difference between momentary values of two points representing two symbols including no redundant bit data and having different values.