On the exam day, you should only carry your admit card along with you to the exam centre. If you are appearing in the offline mode you can also take a clip board along with you. However you must ensure that nothing is written on it. As per the guidelines for JEE Main given by CBSE, you will not be allowed to carry a watch. All the exam hall will have a wall clock.

There are many instructions that you have to follow on the JEE Main day. I have a provided a link below where you will get all information to be followed on the exam day. So please make sure that you go through each point beforehand to avoid any sort of hassle.

JEE Main 2017 exam day guidelines

Also, CBSE has issued a notification related to the rectification of few exam centre adress allotted to the candidates. The roll number series of candidates who have been allotted those centres are also mentioned. Check the corrected JEE Main exam centre address from the link below and in case, you have been allotted that centre make sure to download the revised JEE Main 2017 admit card