A hydraulic control apparatus for controlling a vehicular automatic
transmission including hydraulically operated frictional coupling devices
which are selectively engaged and released to selectively establish gear
positions having respective different speed ratios, and linear solenoid
valves operable to regulate fluid pressures of the respective frictional
coupling devices, each linear solenoid valve including a spool and a
solenoid and being operable between a pressure-regulating state in which
the spool is movable to a position of equilibrium of forces for
regulating an output fluid pressure according to an electromagnetic force
produced by the solenoid, and a non-pressure-regulating state in which
the spool is held at a stroke end thereof at which no output fluid
pressure is generated from the linear solenoid valve, each linear
solenoid valve in the pressure-regulating state being operable to
regulate a fluid pressure of the corresponding frictional coupling device
according to the electromagnetic force, the hydraulic control apparatus
including a pressure-regulation switching portion operable to effect a
determination on the basis of a present state of a vehicle provided with
the automatic transmission, as to whether each non-used linear solenoid
valve, which is one of the linear solenoid valves that is not presently
used to engage the corresponding frictional coupling device, should be
placed in the pressure-regulating state or in the non-pressure-regulating
state, the pressure-regulation switching portion placing each non-used
linear solenoid valve selectively in the pressure-regulating or
non-pressure-regulating states, according to a result of the
determination.