You’ll need a student visa if you’re planning to study here full time and the course is for longer than three months.
Student visa requirements include:
- an offer of place from an educational institution approved by the New Zealand Qualifications Authority
- a written guarantee from an institution or person that suitable accommodation is available to you in New Zealand (if you’re under 18 years)
- evidence of sufficient funds to live on while you are studying
- a return air ticket to your country, or evidence of sufficient funds to buy one.
This is just a summary. You should make sure you get the full details at Immigration New Zealand. You’ll also be able to apply for your student visa online.