A valve control apparatus including a stepping motor coupled to a valve and a motor control unit for controlling the stepping motor is provided. The motor control unit includes a motor control section for applying drive pulses to the pulse motor, a counting section for counting the number of drive pulses applied to the pulse motor, a voltage-drop detecting section for detecting a voltage drop of a drive power supply for the motor control section, and a writing section for writing a count from the counting section in a nonvolatile memory if the voltage-drop detecting section detects the voltage drop.