The Type 97 Chi-Ha (九七式中戦車 チハ, Kyūnana-shiki chū-sensha Chi-ha or simply "Type 97/57") was a medium tank used by the Imperial Japanese Army during the Second Sino-Japanese War, the Battles of Khalkhin Gol against the Soviet Union, and the Second World War. It was the most widely produced Japanese medium tank of World War II.

The 57 mm main gun, designed for infantry support, was a carry over from the Type 89 I-Go medium tank. The suspension was derived from the Type 95 Ha-Go light tank, but used six road wheels instead of four. The 170 hp Mitsubishi air cooled diesel engine was a capable tank engine in 1938.

The Type 97's low silhouette and semicircular radio antenna on the turret distinguished the tank from its contemporaries. After 1941, the tank was less effective than most Allied tank designs. In 1942, a new version of the Chi-Ha was produced with a larger three-man turret, and a high-velocity Type 1 47 mm tank gun. It was designated the Type 97-Kai ("improved") or Type 97 Shinhōtō Chi-Ha (Japanese: 新砲塔チハ; "New turret Chi-Ha").

With the Type 89 I-Go fast becoming obsolete in the late 1930s, the Imperial Japanese Army (IJA) began a program to develop a replacement tank for infantry support. Experience during the invasion of Manchuria determined that the Type 89 was too slow to keep up with motorized infantry. The new medium tank was intended to be a scaled-up four-man version of the Type 95 Ha-Go light tank, although with a two-man turret, thicker armor, and more power to maintain performance.

The Tokyo factory of Mitsubishi Heavy Industries completed a prototype designated Chi-Ha. The second prototype was completed in June 1937. Although the requirement was for a 47 mm gun, it retained the same short-barreled 57 mm gun as the Type 89B tank. However, at the time IJA was also interested in the lighter and less expensive Type 97 Chi-Ni prototype proposed by Osaka Army Arsenal, which had the same 57 mm main gun. With the out-break of the Second Sino-Japanese War on 7 July 1937, the peacetime budgetary limitations were removed and the more capable and expensive Mitsubishi Chi-Ha model was accepted as the new Type 97 medium tank by the army.

Chi (チ) came from Chū-sensha (チュウセンシャ, "medium tank"). Ha and Ni, in Japanese army nomenclature, refer to model number 3 and 4, respectively from old Japanese alphabet iroha. The Type was numbered 97 as an abbreviation of the imperial year 2597, corresponding to the year 1937 in the standard Gregorian calendar. Therefore, the name "Type 97 Chi-Ha" could be translated as "1937's medium tank model 3".

The Type 97 hull was of riveted construction with the engine in the rear compartment. The tank had a four-man crew including a driver, bow machine-gunner, and two men in the turret. In the forward compartment, the driver sat on the right, and bow gunner on the left. The commander's cupola was placed atop the turret. Internal communications were by 12 push buttons in the turret, connected to 12 lights and a buzzer near the driver.

The Type 97 was equipped with a Type 97 57 mm main gun, the same caliber as that used for the earlier Type 89 I-Go tank. The cannon was a short-barreled weapon with a relatively low muzzle velocity, but sufficient as the tank was intended primarily for infantry support. The main gun had no elevation gear, therefore, the gunner used his shoulder to elevate it.