A medical image processing device is configured to set a parameter to be used for detecting a lesion candidate region. For example, the medical image processing device is configured to input a first parameter P1 estimating a dimension of the lesion, calculate a second parameter P2 based on the first parameter P1, calculate a feature amount indicating a shape of an organ surface by using the second parameter in the medical image, and extract the lesion candidate region based on the calculated feature amount.