Japanese submarine I-56 may refer to one of the following submarines of the Imperial Japanese Navy:
- Japanese submarine I-56 (1928), a Kaidai-class cruiser submarine; renamed I-156 in 1942; scuttled in 1946
- Japanese submarine I-56 (1943), a B3-class cruiser submarine; sunk in 1945
This article includes a list of ships with the same or similar names. If an internal link for a specific ship led you here, you may wish to change the link to point directly to the intended ship article, if one exists.