Printed wiring board, circuit board, and control unit

A printed wiring board comprising:

• a pattern for a primary circuit that receives a power supply with a high voltage from a high power source;
• a pattern for a component mounting circuit, which includes a low voltage circuit and a common circuit;
• a pattern for the low voltage circuit that receives a power supply of a low voltage lower than the high voltage;
• a pattern for the common circuit that is used in a case where a high voltage component used for the high voltage is provided and also in a case where a low voltage component used on the low voltage is provided;
• a first insulator that insulates the pattern for the primary circuit from the pattern for the common circuit;
• and
• a second insulator that insulates the pattern for the common circuit from the pattern for the low voltage circuit, wherein
• the low voltage circuit is used in a case where the low voltage component is mounted thereon, and the common circuit is used when either one of the low voltage component and the high voltage component is mounted thereon.