A forward osmosis module or pressure-retarded osmosis module, comprising: a porous outflow pipe for forward osmosis or pressure-retarded osmosis, comprising: a hollow pipe in which a plurality of first via holes and second via holes through which a fluid is introduceable and dischargeable, penetrate the hollow pipe and are formed in a lengthwise direction; a bypass pipe concentrically disposed inside the hollow pipe in the lengthwise direction; and a partitioning plate formed in a circumferential direction of the bypass pipe and disposed in a direction which crosses inside of the hollow pipe, wherein the first via holes are disposed in front of the partitioning plate and the second via holes are disposed at the rear of the partitioning plate in the lengthwise direction, wherein the partitioning plate is arranged to mutually block a fluid introduceable into the front end of the hollow pipe and another fluid introduceable into the hollow pipe through the second via holes; and a plurality of separation membranes which helically wind an external circumferential surface of the porous outflow pipe in a circumferential direction, wherein the bypass pipe is entirely disposed inside the hollow pipe in the lengthwise direction and includes a first portion in which third via holes through which the fluid is introduceable and dischargeable penetrate the bypass pipe and are formed in the lengthwise direction and a second portion in which holes are not formed; wherein the first portion of the bypass pipe is disposed in front of the second portion of the bypass pipe and wherein a plurality of the porous outflow pipes are connected in series so that ends of the bypass pipes are connected to each other, and wherein, in the porous outflow pipes adjacent to each other, a rear end of the second portion of the bypass pipe included in the porous outflow pipe disposed at the front and a front end of the first portion of the bypass pipe included in the porous outflow pipe disposed at the rear are connected to each other; wherein the first portion and the second portion are divided on the basis of the partitioning plate. a porous outflow pipe for forward osmosis or pressure-retarded osmosis, comprising: a hollow pipe in which a plurality of first via holes and second via holes through which a fluid is introduceable and dischargeable, penetrate the hollow pipe and are formed in a lengthwise direction; a bypass pipe concentrically disposed inside the hollow pipe in the lengthwise direction; and a partitioning plate formed in a circumferential direction of the bypass pipe and disposed in a direction which crosses inside of the hollow pipe, wherein the first via holes are disposed in front of the partitioning plate and the second via holes are disposed at the rear of the partitioning plate in the lengthwise direction, wherein the partitioning plate is arranged to mutually block a fluid introduceable into the front end of the hollow pipe and another fluid introduceable into the hollow pipe through the second via holes; and a hollow pipe in which a plurality of first via holes and second via holes through which a fluid is introduceable and dischargeable, penetrate the hollow pipe and are formed in a lengthwise direction; a bypass pipe concentrically disposed inside the hollow pipe in the lengthwise direction; and a partitioning plate formed in a circumferential direction of the bypass pipe and disposed in a direction which crosses inside of the hollow pipe, wherein the first via holes are disposed in front of the partitioning plate and the second via holes are disposed at the rear of the partitioning plate in the lengthwise direction, wherein the partitioning plate is arranged to mutually block a fluid introduceable into the front end of the hollow pipe and another fluid introduceable into the hollow pipe through the second via holes; and a plurality of separation membranes which helically wind an external circumferential surface of the porous outflow pipe in a circumferential direction, wherein the bypass pipe is entirely disposed inside the hollow pipe in the lengthwise direction and includes a first portion in which third via holes through which the fluid is introduceable and dischargeable penetrate the bypass pipe and are formed in the lengthwise direction and a second portion in which holes are not formed; wherein the first portion of the bypass pipe is disposed in front of the second portion of the bypass pipe and wherein a plurality of the porous outflow pipes are connected in series so that ends of the bypass pipes are connected to each other, and wherein, in the porous outflow pipes adjacent to each other, a rear end of the second portion of the bypass pipe included in the porous outflow pipe disposed at the front and a front end of the first portion of the bypass pipe included in the porous outflow pipe disposed at the rear are connected to each other; wherein the bypass pipe is entirely disposed inside the hollow pipe in the lengthwise direction and includes a first portion in which third via holes through which the fluid is introduceable and dischargeable penetrate the bypass pipe and are formed in the lengthwise direction and a second portion in which holes are not formed; wherein the first portion of the bypass pipe is disposed in front of the second portion of the bypass pipe and wherein a plurality of the porous outflow pipes are connected in series so that ends of the bypass pipes are connected to each other, and wherein the first portion and the second portion are divided on the basis of the partitioning plate.