A hydraulic control apparatus for an automatic transmission is provided
with a solenoid valve that outputs a signal pressure during a failure and
does not output a signal pressure during normal operation and a first
clutch apply relay valve that switches between a normal position (the
right half position) and a fail position (the left half position) based
on this signal pressure are provided. During a failure, fail-safe control
is carried out by the first clutch apply relay valve switching to the
fail position. The first clutch apply relay valve inputs the engagement
pressure of the hydraulic servo from the linear solenoid valve when in
the normal position, and is locked in the normal position. Thereby, while
the first clutch is engaged, the second brake apply control valve can be
switched by the signal pressure of the solenoid valve.