move all files on directory to new subdirectory in same directory

Please how to move all files on directory to new subdirectory in same directory ?

Like this:

/volume1/TEST/file1.jpg to /Volume1/TEST/_NEW_FOLDER/file.jpg
/volume1/TEST2/file2.bmp to /Volume1/TEST2/_NEW_FOLDER/file2.bmp
/volume1/TEST3/file3.dwg to /Volume1/TEST3/_NEW_FOLDER/file3.dwg
/volume1/TEST4/file4.(*) to /Volume1/TEST4/_NEW_FOLDER/file4.(*)