In this study, both laboratory and field tests are performed for evaluating the cementation effect on various in-situ tests. A series of calibration chamber test using artificially cemented specimen is conducted for estimate the effect of cementation on CPT, DMT and bender element tests. And the results of SPTs, CPTs and SPS tests on naturally cemented coastal sediment are also analyzed. Calibration chamber tests show that the small strain shear modulus (G max) is more sensitive to the cementation than the measurements by CPT and DMT because the cementation effect is not fully reflected in the CPT and DMT results due to the damage of cementation induced during the penetration. It is also observed that the dilatometer modulus from DMT is more effective to evaluate the cementation effect than the cone resistance from CPT. The calibration chamber and in-situ tests verify that the G max/q c-q c1 and (G max/p a)/N 60-(N 1) 60 relations suggested by Schnaid et al. (2004) are effective to detect the cementation of in-situ sediment. However, the (G max/p a)/N 60-(N 1) 60 relation should be corrected a little for the more exact prediction of cementation level. The observation of in-situ tests on naturally cemented sediment shows the q c/N ratio of Jeju sediments is much higher than that of un-cemented sand on the (q c/p a)/N 60-D 50 relation. It means that SPT is more destructive to cementation bonds than CPT.