A radio communication device which has two antennas (9a, 9b) and uses PADM, Per transmit Antenna Differential Mapping, transmission diversity of performing a different differential phase shift modulation for each of the transmit antennas on signals created on a basis of an identical information sequence, and transmitting the signals, said radio communication device comprising: - an encoding unit (3, 4) for performing an encoding process on an inputted information sequence for each of the transmit antennas; - a delaying unit for delaying a transmission timing of a first one to be transmitted from one of the antennas, among information sequences which said encoding unit creates by encoding the inputted information sequence and which respectively correspond to the two antennas, with respect to a transmission timing of a second one of the information sequences to be transmitted from the other one of the antennas; - an information sequence arrangement changing unit (4, 7) for interchanging two signal points in the first information sequence to change arrangement of said first information sequence; - a mapping unit (6, 7) for mapping the first information sequence, whose arrangement has been changed by the information sequence arrangement changing unit (4, 7), onto a complex plane which consists of a real number axis and an imaginary number axis as signal points, and for mapping the second information sequence onto another complex plane as signal points; and - a modulating unit (8a, 8b) for performing a π/4-shift differential phase shift modulation process on the mapped first information sequence, and for performing a differential phase shift modulation process on the mapped second information sequence, wherein the two signal points interchanged by the information sequence arrangement changing unit (4,7) respectively belong to quadrants of the complex plane which are one of a first quadrant and a third quadrant, a second quadrant and a fourth quadrant, the first quadrant and the second quadrant, the first quadrant and the fourth quadrant, the second quadrant and the third quadrant, and the third quadrant and the fourth quadrant. - an encoding unit (3, 4) for performing an encoding process on an inputted information sequence for each of the transmit antennas; - a delaying unit for delaying a transmission timing of a first one to be transmitted from one of the antennas, among information sequences which said encoding unit creates by encoding the inputted information sequence and which respectively correspond to the two antennas, with respect to a transmission timing of a second one of the information sequences to be transmitted from the other one of the antennas; - an information sequence arrangement changing unit (4, 7) for interchanging two signal points in the first information sequence to change arrangement of said first information sequence; - a mapping unit (6, 7) for mapping the first information sequence, whose arrangement has been changed by the information sequence arrangement changing unit (4, 7), onto a complex plane which consists of a real number axis and an imaginary number axis as signal points, and for mapping the second information sequence onto another complex plane as signal points; and - a modulating unit (8a, 8b) for performing a π/4-shift differential phase shift modulation process on the mapped first information sequence, and for performing a differential phase shift modulation process on the mapped second information sequence,