Provided is an objective and convenient index for judging full recovery from atopic dermatitis and severity thereof. The present invention provides a diagnosis assisting method for determining a treatment policy for an atopic dermatitis subject under the treatment, said method comprising: measuring the expression value of SCCA-1 in skin horny cells of the subject; i) when the SCCA-1 expression value is not statistically significantly higher than the level of those who do not suffer from atopic dermatitis, then determining that the continuation of the treatment for the disease becomes unnecessary thanks to the treatment; and, in the case where the continuation of the treatment is determined as still necessary, ii) ranking the severity of atopic dermatitis of the subject using the SCCA-1 expression value as an index and determining an adequate treatment method for atopic dermatitis to be given to the subject depending on the rank.