An estimation method of estimating the number of living bodies that are present in a space and include at least one living body, the estimation method using (i) a transmission unit including at least one transmission antenna element and (ii) a reception unit including N reception antenna elements where N is a natural number greater than or equal to two, the estimation method comprising: calculating a plurality of complex transfer functions, based on reception signals respectively received by the N reception antenna elements during a predetermined period, the plurality of complex transfer functions each representing propagation characteristics between the at least one transmission antenna element and the N reception antenna elements; extracting a variation component corresponding to each of the N reception antenna elements, from the plurality of complex transfer functions calculated in the calculating of the plurality of complex transfer functions, the variation component being caused by a living body; calculating a correlation matrix based on the variation component corresponding to each of the N reception antenna elements extracted in the extracting; and calculating eigenvalues of the correlation matrix calculated in the calculating of the correlation matrix; estimating the number of living bodies in a predetermined method, using the eigenvalues calculated in the calculating of the eigenvalues, wherein, in the estimating of the number of living bodies, the number of living bodies is estimated based on a feature of an eigenvalue distribution in which the eigenvalues calculated in the calculating of the eigenvalues are sorted by magnitude, wherein the eigenvalue distribution is ratio information indicating a ratio or difference between adjacent eigenvalues among the eigenvalues calculated in the calculating of the eigenvalues when the eigenvalues are sorted by magnitude, the feature is whether the ratio or difference included in the ratio information at an xth eigenvalue from a largest eigenvalue is greater than or equal to a predetermined value, where x is a natural number, and, in the estimating of the number of living bodies, the number of living bodies is estimated to be the natural number indicated by x. calculating a plurality of complex transfer functions, based on reception signals respectively received by the N reception antenna elements during a predetermined period, the plurality of complex transfer functions each representing propagation characteristics between the at least one transmission antenna element and the N reception antenna elements; extracting a variation component corresponding to each of the N reception antenna elements, from the plurality of complex transfer functions calculated in the calculating of the plurality of complex transfer functions, the variation component being caused by a living body; calculating a correlation matrix based on the variation component corresponding to each of the N reception antenna elements extracted in the extracting; and calculating eigenvalues of the correlation matrix calculated in the calculating of the correlation matrix; estimating the number of living bodies in a predetermined method, using the eigenvalues calculated in the calculating of the eigenvalues, wherein, in the estimating of the number of living bodies, the number of living bodies is estimated based on a feature of an eigenvalue distribution in which the eigenvalues calculated in the calculating of the eigenvalues are sorted by magnitude, wherein the eigenvalue distribution is ratio information indicating a ratio or difference between adjacent eigenvalues among the eigenvalues calculated in the calculating of the eigenvalues when the eigenvalues are sorted by magnitude, the feature is whether the ratio or difference included in the ratio information at an xth eigenvalue from a largest eigenvalue is greater than or equal to a predetermined value, where x is a natural number, and, in the estimating of the number of living bodies, the number of living bodies is estimated to be the natural number indicated by x.