A solenoid control apparatus includes a resin housing having a solenoid mounting portion, a connector portion, and a circuit board mounting portion in which a circuit board is mounted. Terminals extending from the solenoid mounting portion and the connector portion are soldered to the electrical circuit on the circuit board. The circuit board has a reduced-rigidity portion in its area corresponding to a portion of the resin housing through which the connector portion is connected to the solenoid mounting portion. The reduced-rigidity portion is formed by reducing the amount of material forming the circuit board per unit area, and is more easily deformable than the remaining portion of the circuit board. When the connector portion is thermally deformed, the circuit board is also easily deformable about the reduced-rigidity portion. This reduces stress on the soldered portions.