Memory system and control method of memory system for controlling of first and second writing operations

A memory system comprising:

• a semiconductor memory device including a first memory string and a second memory string each including a plurality of memory cell transistors electrically coupled in series;
• and
• a memory controller configured to instruct the semiconductor memory device to execute a write operation for writing data on any one of the memory cell transistors in the first memory string or in the second memory string, wherein
• the first memory string and the second memory string are electrically coupled in parallel between a bit line and a source line, and electrically coupled to different word lines,
• the write operation includes a first write operation and a second write operation executed after the first write operation, and
• the memory controller is configured to instruct the semiconductor memory device to execute the first write operation on a second memory cell transistor in the second memory string between the first write operation on a first memory cell transistor in the first memory string and the second write operation on the first memory cell transistor.