Unsupervised multivariate time series anomaly detection (UMTSAD) is important in various domains.Deep learning models based on the Transformer and self-attention mechanisms have shown impressive results in UMTSAD.However, these models have limitations in generalizing to diverse anomaly situations without labeled data.To address this, the proposed model, AMAD, integrates AutoMasked Attention for UMTSAD scenarios, providing a robust and adaptable solution.