The 4th Naval Armaments Supplement Program (マル4計画, 第四次海軍軍備充実計画, Maru 4 Keikaku, Dai-Yo-Ji Kaigun Gunbi Jūjitsu Keikaku) was one of the armaments expansion plan of the Imperial Japanese Navy (IJN).
In 1939, the IJN started new naval armaments expansion plan. It extended to 80 warships and 75 Naval Air Groups by 1.6 billion JPY.
| Category | Class | Vessel number(s) | Completed | Converted | Cancelled |
| Training cruiser | Katori | #101 | Kashii (#101) | ||
| Minelayer | Hatsutaka | #102 | Wakataka (#102) | ||
| Combat support ship | Sunosaki | #103 | Sunosaki (#103) | ||
| Destroyer Type-B | Akizuki | #104–109 | Akizuki (#104), Teruzuki (#105), Suzutsuki (#106), Hatsuzuki (#107), Niizuki (#108), Wakatsuki (#109) | ||
| Battleship | Yamato | #110–111 | #110 was converted to aircraft carrier | #111 | |
| Aircraft carrier | Shinano | Shinano (#110) | |||
| Destroyer Type-A | Kagerō | #112–114 | Arashi (#112), Hagikaze (#113), Maikaze (#114), Akigumo (#115) | #115 was converted from the Yūgumo class | |
| Yūgumo | #115–129 | Yūgumo (#116), Makigumo (#117), Kazagumo (#118), Naganami (#119), Makinami (#120), Takanami (#121), Ōnami (#122), Kiyonami (#123), Tamanami (#124), Suzunami (#126), Fujinami (#127) | #115 was converted to the Kagerō class #125 was converted to the Shimakaze class #128 and #129 were dummy of naval budget of the Yamato-class battleships |
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| Destroyer Type-C | Shimakaze | Shimakaze (#125) | |||
| Aircraft carrier | Taihō | #130 | Taihō (#130) | ||
| Seaplane tender | Akitsushima | #131 | Akitsushima (#131) | ||
| Light cruiser Type-B | Agano | #132–135 | Agano (#132), Noshiro (#133), Yahagi (#134), Sakawa (#135) | ||
| Light cruiser Type-C | Ōyodo | #136–137 | Ōyodo (#136) | #137 | |
| Cruiser submarine Type-A | I-9 | #138 | I-11 (#138) | ||
| Cruiser submarine Type-B | I-15 | #139–153 | I-26 (#139) to I-39 (#152) | #153 was dummy of naval budget of the Yamato-class battleships | |
| Large sized submarine | I-176 | #154–163 | I-176 (#154) to I-185 (#163) | ||
| Minesweeper | No.19 | #164–169 | No.19 (#164) to No.24 (#169) | ||
| Minelayer | Sokuten | #170–179 | Hirashima (#170), Hōko (#171), Ishizaki (#172), Takashima (#173), Saishū (#174), Niizaki (#175), Yurijima (#176), Nuwajima (#177), Maeshima (#178) | #179 | |
| Subchaser | No.13 | #180–183 | No.13 (#180) to No.16 (#183) | ||
| Cable layer | Hashima | [1] | Hashima, Tsurushima, Ōdate, Tateishi | ||
| Food supply ship | No.4006 | [1] | No.4006 (later renamed Kinesaki) | ||
| No.4007 | [1] | No.4007 (later renamed Nosaki) |
