|Taiwanese used the copy of household survey book as one’s personal identification within island, while outside of the island he should depend on passport（ryoken）during Japanese Colonial Period. So the ryoken system was the central part of management of Taiwan's entry and exit control. From this paper we understand that the Formosa Government have no idea about how to block the 2 big leaks through which Taiwanese enter China by transfer from Japan or by illegal emigration. This is why she could do nothing except strengthening controls on issuing passport.
Although the Ministry of Foreign Affairs of Japan stated Taiwanese passports may not be seized, the consulates in China taking great pains to manage Taiwan residences there still were delegated the responsibility to deal with expediency, so they were most likely to use different methods of management for different objects as their convenience, and perhaps this gradually evolved into a way of keeping Taiwanese passports as a formal way.
But the scrutiny and differential treatment on issuing Taiwanese passports could not stop gangsters or anti-Japanese activists from entering China, even resulted in the opposite effect that made these people gathering China. After leading to such a situation, what the consulates and Formosa Government should do was no longer how to put a ban on issuing passport, but how to control gangsters to carry out the southern forward policy and monitor anti-Japanese activists’ actions in China. This maybe why the Formosa Government loosened the law, but on the other hand, varied in the implementation on different people.