A labdane diterpene dialdehyde was first time isolated from the chloroform extract of rhizomes of Curcuma amada. This compound exhibited antitubercular activity (MIC = 500 μg/mL) against Mycobacterium tuberculosis H37Rv strain in BACTEC-460 assay. Two of its semisynthetic analogues also exhibited antitubercular activity at 250–500 μg/mL. It is the first report on isolation and antimycobacterial activity of this dialdehyde from C. amada.