A modular device comprising: a base including a connection electrode exposed to the outside of the modular device; a body including a PCB electrically connected to the connection electrode, the body mounted on the base; a terminal mounted on the body and including a port electrically connected with the PCB; wherein the base comprises: a first case; and a second case coupled to the first case, wherein the first case includes: a first surface (120S1) facing the body; and a plurality of slits (122, 124, 126) formed on the first surface (120S1), wherein the second case comprises: at least one of ribs (112, 114, 116) extending from the base toward the body and inserted into the plurality of slits (122, 124, 126), wherein at least one of the plurality of slits is empty with the at least one of ribs, wherein the PCB comprises a lower receiving portion (222, 224) such that the at least one of ribs (112, 114) is inserted into the lower receiving portion (222, 224). a base including a connection electrode exposed to the outside of the modular device; a body including a PCB electrically connected to the connection electrode, the body mounted on the base; a terminal mounted on the body and including a port electrically connected with the PCB; wherein the base comprises: a first case; and a second case coupled to the first case, wherein the first case includes: a first surface (120S1) facing the body; and a plurality of slits (122, 124, 126) formed on the first surface (120S1), wherein the second case comprises: at least one of ribs (112, 114, 116) extending from the base toward the body and inserted into the plurality of slits (122, 124, 126), wherein at least one of the plurality of slits is empty with the at least one of ribs, wherein the PCB comprises a lower receiving portion (222, 224) such that the at least one of ribs (112, 114) is inserted into the lower receiving portion (222, 224). a first case; and a second case coupled to the first case, wherein the first case includes: a first surface (120S1) facing the body; and a plurality of slits (122, 124, 126) formed on the first surface (120S1), wherein the second case comprises: at least one of ribs (112, 114, 116) extending from the base toward the body and inserted into the plurality of slits (122, 124, 126), wherein at least one of the plurality of slits is empty with the at least one of ribs, wherein the PCB comprises a lower receiving portion (222, 224) such that the at least one of ribs (112, 114) is inserted into the lower receiving portion (222, 224). a first surface (120S1) facing the body; and a plurality of slits (122, 124, 126) formed on the first surface (120S1), wherein the second case comprises: at least one of ribs (112, 114, 116) extending from the base toward the body and inserted into the plurality of slits (122, 124, 126), wherein at least one of the plurality of slits is empty with the at least one of ribs, wherein the PCB comprises a lower receiving portion (222, 224) such that the at least one of ribs (112, 114) is inserted into the lower receiving portion (222, 224). at least one of ribs (112, 114, 116) extending from the base toward the body and inserted into the plurality of slits (122, 124, 126), wherein at least one of the plurality of slits is empty with the at least one of ribs, wherein the PCB comprises a lower receiving portion (222, 224) such that the at least one of ribs (112, 114) is inserted into the lower receiving portion (222, 224).