The invention discloses a sealed sampling device for a gas sample. The sealed sampling device comprises an outer pipe, an inner pipe and a double-layer pipe, wherein the outer pipe comprises a connecting mandrel for controlling slurry to enter and exit from a channel, a drill bit and a connecting pipe assembly positioned between the connecting mandrel and the drill bit; the inner pipe at least comprises a connecting sleeve, an upper ball valve, a sealing pipe and a lower ball valve; one end of the connecting sleeve is rotatably connected to the connecting mandrel in a sleeving manner; a core barrel is arranged between the upper ball valve and the lower ball valve, and serves as a storage carrier of a core; the core barrel can be sealed by closing the upper ball valve and the lower ball valve; the tail end of the double-layer pipe is against the connecting mandrel and can move back and forth under the control of the connecting mandrel; and a control element for controlling the opening and closing of the upper ball valve and the lower ball valve is arranged at the front end of the double-layer pipe, so that the upper and lower ball valves are opened or closed by moving the control element forwards or backwards. Therefore, the device is compact in structure, good in seal effect and wide in application range; and during drilling, only the outer pipe rotates and the rest of components do not rotate, thereby ensuring that the core can smoothly enter the core barrel.