The Castle of Otranto is regarded as the Gothic novel and it has many supernatural elements. Reeve insists that this book has a redundancy in degree of the marvelous, to excite the attention, which palls upon the mind. Also she says the supernatural elements must keep within certain limits of credibility. However, ‘supernatural’ means ‘(of a manifestation or event) attributed to some force beyond scientific understating or the laws of nature’ and originally supernatural things are not existing in reality. A ghost, giant helmet which kills Manfred’s son, or enchanted sword that all of them do not exist in real life so that nobody sees actually even Horace Walpole who is the writer of this book. We, as adult-reader and grown up people who have less imaginative power than children, could say those supernatural and fanciful elements make a novel immature or childish, however, we cannot say ‘this element is out of limitation!’. Even though Reeve tells that imagination is destroyed because of redundancy, imagination has no limitation.