Provided is a method of determining a toggle sequence for error detection based on a soft decision value and a method and apparatus for determining an error pattern, and more particularly, to a method of determining an optimum toggle sequence and error pattern based on a soft decision value in order to allow for faster error (pattern) detection and correction. It is an object of the invention to implement low redundancy, less delay, and a receive-side error correction capability by combining advantages of the conventional ARQ scheme and the conventional FEC scheme using a soft decision reliability. For this purpose, according to a first embodiment of the present invention, in order to optimize the toggle sequence speed, there is provided a method of determining a toggle sequence such that bits are toggled sequentially in the order of a smaller sum of soft decision reliabilities to be toggled.