The Central Materials Laboratory is an organization within the Public Works Department, Sarawak that comes directly under the Geotechnical and Structural Engineering Branch of JKR Headquarters. It is specially set up for ensuring quality control of engineering materials and carrying out geotechnical investigation of sites of proposed government projects located throughout Sarawak.

The Central Materials Laboratory is also a referral center for other JKR Divisional Laboratories for technical assistance in laboratory testing, site investigations, technical training, and geotechnical data. The laboratory is also responsible for supplying test equipment to the divisional laboratories and carrying out calibration works. Recently, two (2) new units namely the Forensic Unit and the R&D Unit were established to meet new expectations of CML customers and stakeholders.