Definition
In Korea, the restoration duty is the legal promise to return a rented home or shop to the original condition it was in when you got it, once the lease ends and you move out. It comes from Korea's Civil Code (Article 615, applied to leases by Article 654), which says a tenant must restore the property when giving it back.
The basic rule: give back what you borrowed, as you got it
If you borrow a clean comic book from a friend, you'd return it without scribbles. A rental contract works the same way. While you pay a deposit and use someone else's home or shop, you can live there freely. But when the contract ends, you have to put it back the way it looked when you received it.
Say you needed a big shelf on the living room wall, or you cut a pet door into a bedroom door. What then? When you move out, you take down the shelf and fill the holes, or repair the damaged door, before handing the place back to the landlord.
This responsibility to tidy up and return something borrowed in its original form is called the restoration duty (literally, the duty to restore the original state). It arises under the law even if the contract doesn't mention it. A special clause in the contract can change how far it goes.
How far do you have to fix things?
So do you have to fix every worn spot from years of living there, until it looks brand new? Short answer: no. The natural wear and fading that come from people simply living in a home are called ordinary wear and tear in the law.
If sunlight turned the living room wallpaper yellow, or a wardrobe left natural dents in the floor, the tenant doesn't have to pay for it. Courts see natural aging as something a lease expects from the start. Making the tenant fix it would give the landlord an unfair gain.
More precisely, what has to be restored is anything the tenant newly installed, plus damage caused on purpose or through the tenant's fault. For example, if you hammered in many thick nails and cracked the concrete, or indoor smoking badly stained the wallpaper, you pay to repair it yourself.
The smartest way to avoid disputes
Fights over restoration usually blow up on moving day, when you're getting your deposit back. The landlord says it was perfect before and wants to take repair costs out of the deposit. The tenant says it wasn't clean even when they moved in.
The surest way to prevent this is to take careful photos on move-in day. Before the boxes come in, photograph or film every scratch, floor dent, and tile crack, and share them with your landlord in a message.
If you do work that touches the structure, like mounting a TV on the wall or drilling a hole for an air conditioner, get the landlord's consent first. Also leave a written record, such as a text, of how you'll handle it when you move out. That helps you avoid pointless disputes later.
Common misconceptions
When you move out, you must repair everything that wore down while you lived there, until it's like new.
Wear that happens naturally over time (ordinary wear and tear) doesn't need to be restored. What you must restore is anything you installed, or anything you damaged on purpose or through carelessness.
Where you meet it
If you drilled a big hole in the wall to mount a TV, you need to fill it before you move out.
Wallpaper that faded from sunlight is natural aging, so you don't have to pay to have it replaced.
In one sentence
It's the duty to return a rented space as you got it. Natural aging is excluded, and you restore what you installed yourself or damaged through carelessness.