Thank you for reply.
I examined, on /etc/usbmount/usbmount.conf follow is ok.
FS_MOUNTOPTIONS="-fstype=vfat,gid=pi,dmask=0000,fmask=0111"
but adding iocharset and codepage seems to be an error.
(ex. FS_MOUNTOPTIONS="-fstype=vfat,iocharset=utf8,codepage=932,gid=pi,dmask=0000,fmask=0111")
Since raspbian (on Raspberry Pi) can work without problems, will not it be possible for armbian to work properly?