To provide a playing tool provided with a domed air chamber, which is easy to build or take into pieces any time and at any places and easy to carry and store.

This play tool comprises a main body air chamber 2, which is constituted of an upper sheet 5 and a lower sheet 7 formed by dome shaped air-impermeable sheets placed to face each other and stuck together at the peripheral parts, and a lower chamber 4 formed by the lower sheet 7, the ring peripheral air chamber 3 formed on the peripheral part of the lower face of the main body air chamber 2, and a bottom sheet 8 spread under the peripherial air chamber 3. A hose 10 with a valve 11 is fixed to each of the mainbody air chamber 2, the peripheral air chamber 3, and the lower air chamber 4. A gap protection pad 12 is stuck on the grounding face of the peripheral air chamber 3, and the periphery of the peripheral air chamber 3 is provided with domed air chamber suspending lifelines 13 for anchoring.