A fail-safe sequential machine is one that produces error signal when failures occure in the machine. This paper presents a new method of realization of fail-safe sequential machines under the following assumptions:

1) failure is caused by faults of logical and memory elements in the machine,

2) output of faulty elements is stuck at one or zero.

A feature of this method is that an input inversion is used for additional state assignment and this additional state is used for detection of faults of elements.