Provision of a waterproof device capable of improving waterproof property in a push-in operation portion formed by including an extensible member, a holding member and an operation shaft. A
wrist watch (portable device) 11 includes an outer case (device outer housing) 12, an extensible member 32 with waterproof property, a holding member 41 attached to the case 12 and an operation shaft 51. The case 12 includes a seating portion 29 and a hole 30. The extensible member 32 includes a cylindrical portion 33 which can be extended / retracted in an axial direction, closing one end as well as opening the other end, and inserted into the hole 30, and a
flange 35 projecting integrally from an outer periphery of the other end portion of the cylindrical portion and seated on the seating portion 29. The holding member 41 includes a presser portion 42 sandwiching the
flange 35 with the seating portion 29 to thereby secure the
waterproofing around the
flange, and a through hole 44 connecting to the opening of the cylindrical portion 33. The operation shaft 51 includes a shaft end portion 52 protruding to the outside of the holding member 41 through the through hole 44. The operation shaft 51 is inserted into the cylindrical portion 33 and arranged in a state of being able to be pushed from the outside of the case 12 so as to allow the cylindrical portion 33 to extend.