How to store AMI file to S3 bucket?

It is not possible to export an AMI.

An Amazon Machine Image (AMI) is a copy of an Elastic Block Store (EBS) volume. The AMI is stored in Amazon S3, but it is not accessible via the S3 service. Think of it as being stored in AWS's own S3 bucket, rather than yours.

If you wish to export a disk image, use a standard disk utility to copy the disk to ISO format, which can then be copied and mounted on other VMs.

Thank you John.

Hi Guys, I had chat with AWS support also. For your reference ,

10:15:45 AM Myself: Well i have some doubts. I will ask and just clear in me on that. 
10:15:49 AM AWS support: Sure 
10:15:59 AM AWS support: I'll be happy to do so 
10:16:25 AM Myself: Is there any option to sore AMI in S3 bucket. 
10:16:46 AM AWS support: No, this is not possible 
10:17:05 AM AWS support: AMI data is a simple configuration file 
10:17:11 AM AWS support: This is backed by S3 
10:17:18 AM AWS support: But not stored in an S3 bucket 
10:17:27 AM AWS support: The exact same is true for Snapshots 
10:17:45 AM AWS support: It is stored and backed by S3- but not something that can be placed in one of your buckets 
10:17:59 AM Myself: is it possible to view that in s3? 
10:18:51 AM AWS support: No, this is not something that is visible in S3, I am sorry to say 
10:19:57 AM Myself: OK. I need to download the AMI . what can i do? 
10:20:19 AM AWS support: AMI data is not something that is downloadable 
10:20:35 AM AWS support: Are you seeking to Download your whole instance? 
10:20:46 AM AWS support: Or download a complete volume? 
10:21:07 AM AWS support: If you originally imported your instance from a VM, you can Export the VM 10:21:29 AM AWS support: But its an EC2 instance that was created in EC2, you can not- I am really sorry to say 
10:22:02 AM Myself: Okay fine.