  The linear-chain states of $^{14}$C are theoretically investigated by using
the antisymmetrized molecular dynamics. The calculated excitation energies and
the $\alpha$ decay widths of the linear-chain states were compared with the
observed data reported by the recent experiments. The properties of the
positive-parity linear-chain states reasonably agree with the observation, that
convinces us of the linear-chain formation in the positive-parity states. On
the other hand, in the negative-parity states, it is found that the
linear-chain configuration is fragmented into many states and do not form a
single rotational band. As a further evidence of the linear-chain formation, we
focus on the $\alpha$ decay pattern. It is shown that the linear-chain states
decay to the excited states of daughter nucleus $^{10}{\rm Be}$ as well as to
the ground state, while other cluster states dominantly decay into the ground
state. Hence, we regard that this characteristic decay pattern is a strong
signature of the linear-chain formation.
