A member to be compressed for an electrochemical device obtained by crosslinking a crosslinkable composition containing a fluorine-containing elastomer containing a unit based on at least one crosslinkable group-containing monomer selected from the group consisting of a crosslinkable group-containing monomer (1) represented by the general formula (1): CX12═CF—Rf1—X2 wherein each X1 independently represents H or F, and Rf1 represents a fluorinated alkylene group or a fluorinated oxyalkylene group, and X2 represents I or Br; and a crosslinkable group-containing monomer (2) represented by the general formula (2): CX32═CX3—Z1—CX3═CX32 wherein each X3 independently represents H, F, an alkyl group or a fluorinated alkyl group, and Z1 represents an alkylene group, a fluorinated alkylene group, a cycloalkylene group, a fluorinated cycloalkylene group, an oxyalkylene group or a fluorinated oxyalkylene group.