Depending on the nature of the activities you want to do. If your business is processing the agricultural stuffs then it should be fine.

Also, on land titles with agricultural category, you can build a house for own/employee (agricultural activities) stay, provided the house occupy less than 1/5 of the whole area of the land or 2 hectares, whichever is lesser.

If you intend to do other things than that, you will need to apply to land office to change the category of land use to either building or industry (town planner to submit for planning approval first, then land surveyor to apply for conversion), then architect and engineers to submit building plans, only can start building after obtaining all approvals. After finish building, testing and investigation, architect will issue a certificate of completion and compliance (CCC), only then the owner can move in and occupy the buildings.

If you want to operate business, you will still need to apply for business license, of which they will require you to produce the CCC for application.

You may refer to National Land Code 1965 and Town and Country Planning Act 1976 for more details.