The Japanese Navy included five Type A midget submarines in the Pearl Harbor raid of 7 December 1941. Transported on board large I type submarines, the midgets were launched near the entrance to Pearl Harbor the night before the attack was to begin. One, spotted trying to enter the harbor before dawn, was attacked by USS Ward (DD-139) and presumably sunk in the first combat action of the as yet unopened Pacific War. At least one of the midgets was able to enter the harbor and was sunk there by USS Monaghan (DD-354). Another, the Ha-19, unsuccessful in its attempts to penetrate Pearl Harbor, drifted around to the east coast of Oahu and was captured there the day after the attack.

Three of the five Pearl Harbor midget submarines have been salvaged, Ha-19 immediately after the attack and the one sunk by USS Monaghan a few days later. The third was found off the harbor entrance in 1960. Monaghan's submarine was buried in a landfill shortly after its recovery. The other two are on exhibit, Ha-19 at Fredericksburg, Texas, and the one found in 1960 at Eta Jima, Japan.

The two remaining midgets are still unaccounted for, including the one attributed to USS Ward. Recent studies of Pearl Harbor attack photograpy have led some observers to argue that one of the midgets was in place off "Battleship Row" as the Japanese torpedo planes came in, and may have fired its torpedoes at USS Oklahoma (BB-37) or USS West Virginia (BB-48). This contention is still controversial, but, if it is true, one Type A midget submarine may lie undiscovered inside Pearl Harbor.