To solve the following problems: conventionally, heat insulation effect is achieved by separating a heat generating device arranged in a vehicle controller from a device whose temperature exceeds a prescribed temperature due to the generated heat, or by installing a heat insulation panel, however there is little or no space for heat insulation in a compact controller, or the devices are sometimes installed adjacent to each other due to the performance of the device or requests from a customer.

A tubular hole is formed in a part of a BOX for accommodating the device to form a wind tunnel 5, to obtain heat insulating effect, where the devices are adjacent to each other.