Go to System -> Import/Export -> Dataflow profiles.
(NOT to Magento admin->System->Import/Export->Import!)
Then, select profile: Import Customers (or create if it not exists).
Set the Store value in the Profile information box to the 'Default store view'. Then, upload Your CSV, and run the profile.
You can use the CSV header like below:
id website firstname lastname email password_hash billing_firstname billing_lastname billing_company billing_postcode billing_city billing_street1 billing_telephone billing_country billing_region shipping_firstname shipping_lastname shipping_company shipping_postcode shipping_city shipping_street1 shipping_telephone shipping_country shipping_region is_subscribed group group_id dob