An abnormality detection apparatus of an engine temperature adjusting thermostat is provided which is capable of accurately grasping the state of an amount of heat generated by an engine to prevent misdetection of abnormality in the thermostat for improved reliabilty. A linearity compensation circuit 8 is inserted upline from the tuner 7. If one or more stop devices fails to acknowledge the initial start message, one or more start messages are transmitted including an elapsed time since the initial start message. The removable door check device of the hinge is disposed on the hinge pin exterior to the first and second hinge parts engaging the second hinge part in the opened position.