A fuel evaporative gas treatment device for a fuel tank is used in a motorcycle including a combustion engine with a supercharger. The fuel evaporative gas treatment device includes a canister which contains an adsorbent for adsorbing fuel evaporative gas from the fuel tank, a communication passage which communicates between an air intake passage for the combustion engine and the canister, and a check valve provided on the communication passage. The check valve blocks fluid flow from the air intake passage to the canister and permits fluid flow from the canister to the air intake passage.