Elements of a combinational circuit are divided into plural groups. The
output from a terminal Q is fixed at shifted timing in flip-flop circuits
belonging to each of groups X, Y and Z resulting from this grouping. With
the outputs from the terminals Q of the flip-flop circuits thus fixed, an
operation of a shift mode is carried out. When the operation of the shift
mode is completed, a hold releasing operation and a capture operation are
carried out with respect to each of the groups of the flip-flop circuits.
For example, the hold releasing operation is carried out when one clock
is at a high level with the capture operation carried out when the clock
is at a low level, or the hold releasing operation is successively
carried out with respect to each of the groups and then the capture
operation for capturing a data signal is carried out with respect to each
of the groups.