This disclosure provides a waterproof electronic component having good waterproofness and a method for assembling the waterproof electronic component. A repeater as a waterproof electronic component includes (i) a substrate having first through holes, (ii) a socket fixed to the substrate, (iii) a housing containing the substrate, (iv) a pin held by the housing and having a first end connected to the substrate, and (v) a sealing section with which an area surrounded by the substrate and the housing is filled, the housing including a support including a supportive wall section capable of supporting a fixation portion of the socket and a seat section having a seating surface on which the substrate is placed, the substrate being placed on the seat section, the socket being oriented in such a manner that at least a portion of an outer surface of the fixation portion is close to and faces the supportive wall section.