diff --git a/rest_framework/fields.py b/rest_framework/fields.py
index baa932b2d..a89e79b10 100644
--- a/rest_framework/fields.py
+++ b/rest_framework/fields.py
@@ -878,7 +878,7 @@ class FloatField(Field):
             self.fail('invalid')
 
     def to_representation(self, value):
-        return float(value)
+        return float(value) if value is not None else None
 
 
 class DecimalField(Field):