A control apparatus and control method of an automatic transmission that
establishes a plurality of speeds of different speed ratios by
selectively engaging and/or releasing a plurality of engagement devices,
detects abnormal engagement of at least one of the engagement devices
which causes tie-up to occur in the automatic transmission; establishes a
predetermined specific speed set in advance in order to prevent tie-up
from occurring in the automatic transmission, when abnormal engagement of
the at least one of the engagement devices is detected; and places the
automatic transmission in a neutral state when an engine speed will
exceed a predetermined allowable speed if the predetermined specific
speed is established.