You can password protect the workbook, however Excel protection is weak and
easily overcome by anyone with a little knowledge and the will to do so,
Regards,
Alan.
Use Tools > Protection > Protect Workbook. This will do the trick, bu
you haven't given much information in this post so it may stop you doin
other things that you intend to do with the file.
Also, bear in mind that this security isn't that strong and can b
removed fairly easily.