Overview
There is no single national exam for ordinary police officers in Japan. Each prefectural police headquarters (including the Tokyo Metropolitan Police) recruits its own officers, and the National Police Agency (警察庁) runs a recruitment information site that links to each headquarters' own recruitment page. The National Police Agency also recruits its own staff separately, through the national civil service exams, which are not covered here.
Exam dates, categories, age limits and test content are set by each prefectural police headquarters, and this page does not state them because the National Police Agency's pages do not. Pick the prefecture you want to serve in and read its recruitment page. The Agency's pages are in Japanese.
How to apply
Use the National Police Agency's link page to open the recruitment page of the prefectural police headquarters you want, then follow its application instructions.
After the exam
People who pass a prefectural police entrance exam enter that prefecture's police school and start at the rank of patrol officer (巡査). Police officers are local public servants on a salary set by each prefecture. The Agency says police school students are paid, and that there are no tuition fees, though textbooks and judo or kendo uniforms are bought personally. As an example from Ibaraki Prefecture's police school, students are expected to hold a driving licence, and the Agency suggests getting one before entry, removing any automatic-only restriction. Ibaraki's school gives no judo or kendo experience requirement, and says most students start without it. Rules differ by prefecture.
Promotion is by exams and by performance and length of service. The Agency says a university graduate can normally sit the first promotion exam after about two years, and others after about four years.
Preparation tips
Because each prefecture sets its own recruitment rules, prepare from the recruitment page of the prefecture you apply to. Getting a driving licence early is advised by the Agency.
Is there a single national police officer exam in Japan?
No. Each prefectural police headquarters recruits its own officers.
Do police school students pay tuition?
No. Students are paid a salary, though they buy items such as textbooks and judo or kendo uniforms themselves.