A heat exchanger module unit comprising: a multiple number of plates, each of the multiple number of plates having a partition formed with a through-hole, through which a fluid and a heat medium move, each of the plates being stacked with a spacing gap, through which the fluid and the heat medium move, at one side of the partition; and a connector configured to connect respective through-holes, the connector selectively connecting the spacing gaps to form a fluid passage and a heat medium passage through which the fluid and the heat medium move independently respectively; wherein the connector includes a connection ring connecting the through-hole formed in one partition of two adjacent partitions and the through-hole formed in the other partition of the two adjacent partitions and sealing the two through-holes of the two adjacent partitions from the outside; and wherein the connector includes an extension protrusion extending from one partition of the two adjacent partitions toward the other partition of the two adjacent partitions, wherein a receiving recess in which the connection ring is received is formed in the extension protrusion, said receiving recess coming into close contact with the other partition and constituting a plate in the vicinity of the through hole; a phase-change material; wherein the spacing gap in which the phase-change material is received is located and disposed between the spacing gaps which form the fluid passage and the heat medium passage through which the fluid and the heat medium move respectively, wherein heat exchange is made between the fluid and the heat medium through the phase-change material, and wherein one of the fluid and the heat medium is arranged at one side of the phase-change material and another phase-change material is arranged at the opposite side of the phase-change material. a multiple number of plates, each of the multiple number of plates having a partition formed with a through-hole, through which a fluid and a heat medium move, each of the plates being stacked with a spacing gap, through which the fluid and the heat medium move, at one side of the partition; and a connector configured to connect respective through-holes, the connector selectively connecting the spacing gaps to form a fluid passage and a heat medium passage through which the fluid and the heat medium move independently respectively; wherein the connector includes a connection ring connecting the through-hole formed in one partition of two adjacent partitions and the through-hole formed in the other partition of the two adjacent partitions and sealing the two through-holes of the two adjacent partitions from the outside; and wherein the connector includes an extension protrusion extending from one partition of the two adjacent partitions toward the other partition of the two adjacent partitions, wherein a receiving recess in which the connection ring is received is formed in the extension protrusion, said receiving recess coming into close contact with the other partition and constituting a plate in the vicinity of the through hole; a phase-change material; wherein the spacing gap in which the phase-change material is received is located and disposed between the spacing gaps which form the fluid passage and the heat medium passage through which the fluid and the heat medium move respectively, wherein heat exchange is made between the fluid and the heat medium through the phase-change material, and wherein one of the fluid and the heat medium is arranged at one side of the phase-change material and another phase-change material is arranged at the opposite side of the phase-change material.