A symbol mapping device comprising: a transmission data processing unit to receive two pieces of transmission data having a same length, and in a case in which the length is a first length, to use the two pieces of transmission data as two pieces of output data without change, and in a case in which the length is less than the first length, to add dummy data to the two pieces of transmission data to generate two pieces of output data, each piece having the first length; a parity addition unit to generate two pieces of parity-added transmission data on a basis of the two pieces of output data, the two pieces of parity-added transmission data each containing parity data added to the transmission data and each having a second length; a modulation data extraction unit to extract two pieces of modulation data, being data to be mapped, from the two pieces of parity-added transmission data generated by the parity addition unit; and a mapping processing unit to map the two pieces of modulation data to two time slots of constellation points, wherein the parity addition unit includes a first parity generation unit to generate one of the two pieces of parity-added transmission data on a basis of one of the two pieces of output data, and a second parity generation unit to generate another one of the two pieces of parity-added transmission data on a basis of another one of the two pieces of output data, the first parity generation unit and the second parity generation unit each include a first bit extraction unit (21A, 21B) to extract a first number of bits of data from the output data, the first number being less than a number of bits of the output data, and to output the first number of bits of data as a portion of data of the parity-added transmission data having the second length, a second bit extraction unit (22A, 22B) to extract a second number of bits of data from the output data, the second number being less than the number of bits of the output data, and a look-up table circuit (23A, 23B) to generate remaining data other than the portion of data, of the parity-added transmission data having the second length, on a basis of the second number of bits of data, and the number of bits of the parity data differs depending on the number of bits of the transmission data per time slot. a transmission data processing unit to receive two pieces of transmission data having a same length, and in a case in which the length is a first length, to use the two pieces of transmission data as two pieces of output data without change, and in a case in which the length is less than the first length, to add dummy data to the two pieces of transmission data to generate two pieces of output data, each piece having the first length; a parity addition unit to generate two pieces of parity-added transmission data on a basis of the two pieces of output data, the two pieces of parity-added transmission data each containing parity data added to the transmission data and each having a second length; a modulation data extraction unit to extract two pieces of modulation data, being data to be mapped, from the two pieces of parity-added transmission data generated by the parity addition unit; and a mapping processing unit to map the two pieces of modulation data to two time slots of constellation points, wherein the parity addition unit includes a first parity generation unit to generate one of the two pieces of parity-added transmission data on a basis of one of the two pieces of output data, and a second parity generation unit to generate another one of the two pieces of parity-added transmission data on a basis of another one of the two pieces of output data, a first parity generation unit to generate one of the two pieces of parity-added transmission data on a basis of one of the two pieces of output data, and a second parity generation unit to generate another one of the two pieces of parity-added transmission data on a basis of another one of the two pieces of output data, the first parity generation unit and the second parity generation unit each include a first bit extraction unit (21A, 21B) to extract a first number of bits of data from the output data, the first number being less than a number of bits of the output data, and to output the first number of bits of data as a portion of data of the parity-added transmission data having the second length, a second bit extraction unit (22A, 22B) to extract a second number of bits of data from the output data, the second number being less than the number of bits of the output data, and a look-up table circuit (23A, 23B) to generate remaining data other than the portion of data, of the parity-added transmission data having the second length, on a basis of the second number of bits of data, and a first bit extraction unit (21A, 21B) to extract a first number of bits of data from the output data, the first number being less than a number of bits of the output data, and to output the first number of bits of data as a portion of data of the parity-added transmission data having the second length, a second bit extraction unit (22A, 22B) to extract a second number of bits of data from the output data, the second number being less than the number of bits of the output data, and a look-up table circuit (23A, 23B) to generate remaining data other than the portion of data, of the parity-added transmission data having the second length, on a basis of the second number of bits of data, and the number of bits of the parity data differs depending on the number of bits of the transmission data per time slot.