In this report, several methods for estimating direcinstability of the estimate caused by the errors contained in the cross-power spectra, and a new method based on the Bayesian approach is proposed.
　The proposed methods is examined by numerical simulations, and the reliability of the method is discussed. Some examples of the directional spectra estimated from field observation at an offshore oil rig with the use of 7 wave probes are also shown.
　The major conclusions are as follows:
1) The proposed method can be applied for arbitrary mixed instrument array measurements.
2) It has higher resolution power for estimating directional spectrum than other methods.
3) It is a robust method for estimating directional spectrum from the cross-power spectra contaminated by the estimation errors.
4) It is a flexible methods to be able to develop the formulation of the estimation equation as the study of directional seas make progress more deeply.