A printing system includes a host apparatus configured to transmit a command to a printer, and a printer configured to perform processing based on the command received from the host apparatus. The host apparatus is configured to convert the command based on a conversion condition when the command satisfies a predetermined condition, and transmit a conversion code obtained through the conversion to the printer as the command. The printer includes a receiver configured to receive the command from the host apparatus, a command converter configured to discriminate whether the received command is the conversion code obtained through the conversion based on the conversion condition, and when the command is the conversion code, convert the conversion code into the command based on the conversion condition, and a command processor configured to execute the command obtained through the conversion by the command converter when the command is the conversion code, and execute the received command when the command is not the conversion code.