A seal detecting device and means for detecting a leakage on an outer case of an electronic device include providing a through hole on the outer case of the electronic device, an inner side of the electronic device is connected to an outer side of the electronic device; providing an airtight container, placing the outer case of the electronic device into the airtight container, one of the inner side and outer side of the outer case is defined as a gas supply side, and the other side is a detecting side; supplying compressed gas to the gas supply side; leading the detecting side to outside and detect a gas flow, so as to detect if there is a leakage on the outer case of the electronic device. The device and means have the advantages of high sensitivity, quick detecting speed, and high accuracy.