An area code map is a visual representation on a map showing which area codes are assigned to which regions across Japan. It allows intuitive understanding of number distribution patterns and is useful for quickly estimating the origin of calls from unknown numbers.
Japan's area codes were systematized as nationwide automatic dialing (establishing direct-dial capability from anywhere in the country) was rolled out, and as a broad tendency the numbers increase from north to south. Based on the list of area codes published by Japan's Ministry of Internal Affairs and Communications (as of March 1, 2026), the main correspondences are as follows: 01 covers Hokkaido plus Aomori, Akita, and Iwate; 02 covers Miyagi, Yamagata, Fukushima, northern Kanto (Ibaraki, Tochigi, Gunma), Niigata, and Nagano; 03 is Tokyo's 23 wards and parts of the adjoining municipalities; 04 covers Tokyo's Tama area, Kanagawa, Chiba, and Saitama; 05 covers Chubu and Tokai (Aichi, Gifu, Shizuoka, Mie) plus Yamanashi; 06 is Osaka city and its surroundings; 07 covers Kinki and Hokuriku (Toyama, Ishikawa, Fukui); 08 covers Chugoku and Shikoku; and 09 covers Kyushu and Okinawa. The ministry describes a number block as an area within which calls can be dialed starting from the local number, and in the same list area codes run from two to five digits including the leading 0, with the area code and local number together always totaling six digits.
However, this mapping is only a broad tendency, and exceptions are numerous (some blocks starting with 02 include parts of Saitama Prefecture, so prefectures beyond those listed above also appear in the list). For example, the two-digit area code 04 is assigned to Abiko, Kashiwa, Nagareyama, and Noda in Chiba Prefecture, to Kamogawa in Chiba Prefecture, and to Iruma, Sayama, and Tokorozawa in Saitama Prefecture, so "04 = Kanagawa" is not always true. A single number block can also cross prefectural borders: the 06 block includes Amagasaki in Hyogo Prefecture. The same area code can appear in more than one prefecture as well, such as 076 (Toyama and Ishikawa) and 088 (Tokushima and Kochi). Number blocks are not aligned neatly with municipal boundaries either, and within one city the blocks can differ by town or district. Also, among numbers starting with 0 as a prefix, 050 (IP phone), 070/080/090 (mobile phone), 0120 (toll-free), and 0570 (Navi-Dial) are not tied to geographic regions and are not included in area code maps.
A practical use of area code maps is estimating the origin of suspicious calls. For example, a number starting with 06 suggests a call from the Osaka area, and if you have no connection to that region, you can suspect a nuisance call. However, if caller ID spoofing is used, the displayed number and actual origin may differ, so overreliance is unwise. See How to Look Up Area Codes for specific steps to identify regions from numbers and How Japanese Phone Numbers Work for the overall numbering system.