model.py

class Departament(models.Model):
	name = models.CharField(max_length=100)
	description = models.CharField(max_length=500, blank=True)
	status = models.BooleanField(default=False, blank=True)
	created_at = models.DateTimeField(auto_now_add=True, blank=True)

	def __unicode__(self):
		return self.name

class Area(models.Model):
	departament = models.ForeignKey(Departament, on_delete= models.CASCADE, related_name="areas")
	description = models.CharField(max_length=500, blank=True)
	name = models.CharField(max_length=100)
	status = models.BooleanField(default=False, blank=True)
	created_at = models.DateTimeField(auto_now_add=True, blank=True)

	def __unicode__(self):
		return self.name

serializer.py

class AreaSerializer(serializers.ModelSerializer):

	class Meta:
		depth = 1
		model = Area

class DepartamentSerializer(serializers.ModelSerializer):
	areas = AreaSerializer(read_only=True, many=True)

	class Meta:
		model = Departament
		fields = ('id' ,'name', 'description','status', 'areas', 'created_at',)