分裂をする

You usually pair this with the particle が to show what is splitting. For example, 細胞が分裂をする (the cell divides). It focuses on the process of the split itself. Because it uses をする, it adds a bit of action and emphasis to the event. It’s a great word for when you want to sound precise or serious about a separation.

Use this in a biology lab when talking about organisms. It’s also perfect for the evening news when a political party falls apart. You can use it in business if a company splits into two rival firms. If your group of friends has a massive argument and stops hanging out, this word captures that drama perfectly. It’s for big, structural changes.

Don't use this for simple things like cutting a pizza. That would be 切る or 分ける. Also, don't use it for splitting a bill at a restaurant. That is strictly 割り勘. If you tell a waiter you want to 分裂をする the check, they might think you’re planning a scientific experiment at the table. It’s too heavy for casual physical dividing.

Japan deeply values 和 (wa), or social harmony. Because of this, 分裂 is often seen as a negative or tragic event in a social context. It suggests a failure to maintain unity. Historically, Japan has seen many political 分裂 during the Warring States period. Today, it’s a buzzword whenever a famous idol group or organization has internal drama.

You will often see 細胞分裂 (cell division) in science textbooks. In the news, you might hear 内部分裂 (internal split) when a group fights from within. If the split is particularly messy, people might say 空中分解 (falling apart in mid-air). While 分裂する is more common, adding を makes the action feel more deliberate or noteworthy.