In order to investigate relationships between superconducting phase and charge ordered one, the uniaxial strain method is applied to the superconducting salt alpha-(BEDT-TTF)(2)NH4Hg(SCN)(4) and the organic conductor alpha-(BEDT-TTF)(2)CSCd(SCN)(4). Both salts preserve metallic states under a-axial strain and show insulating behaviours under c-axial strain. These results suggest that i) c-axial strain controls the electronic properties of the a-type salts, and ii) the insulating state in the vicinity of the superconducting phase of alpha-(BEDT-TTF)(2)NH4Hg(SCN)(4) is a charge ordered phase, as expected from the comparison in the lattice parameters with the charge ordered salt theta-(BEDT-TTF)(2)RbZn(SCN)(4).