To convert (type convert) character string type data showing a binary number supplied from an input device, such as a serial port, a keyboard, and a barcode reader into numeric type data, such as an integer type and a floating point type in a simple method from the standpoint of suppressing a memory capacity to be mounted in a system.

A data conversion method includes determining each character of n pieces of character data showing a binary number of n digits, and converting the n pieces of character data into numeric data other than a binary number on the basis of a determination result of character data.