var today = new Date();
var num_month = today.getMonth();
var month;

if (num_month == 0){
	month = '<img src="image/top_mainvisual01.jpg" alt="NEXT CHALLENGE" width="732" height="284">';
} else if (num_month == 1){
	month = '<img src="image/top_mainvisual02.jpg" alt="NEXT CHALLENGE" width="732" height="284">';
} else if (num_month == 2){
	month = '<img src="image/top_mainvisual03.jpg" alt="NEXT CHALLENGE" width="732" height="284">';
} else if (num_month == 3){
	month = '<img src="image/top_mainvisual04.jpg" alt="NEXT CHALLENGE" width="732" height="284">';
} else if (num_month == 4){
	month = '<img src="image/top_mainvisual05.jpg" alt="NEXT CHALLENGE" width="732" height="284">';
} else if (num_month == 5){
	month = '<img src="image/top_mainvisual06.jpg" alt="NEXT CHALLENGE" width="732" height="284">';
} else if (num_month == 6){
	month = '<img src="image/top_mainvisual07.jpg" alt="NEXT CHALLENGE" width="732" height="284">';
} else if (num_month == 7){
	month = '<img src="image/top_mainvisual08.jpg" alt="NEXT CHALLENGE" width="732" height="284">';
} else if (num_month == 8){
	month = '<img src="image/top_mainvisual09.jpg" alt="NEXT CHALLENGE" width="732" height="284">';
} else if (num_month == 9){
	month = '<img src="image/top_mainvisual10.jpg" alt="NEXT CHALLENGE" width="732" height="284">';
} else if (num_month == 10){
	month = '<img src="image/top_mainvisual11.jpg" alt="NEXT CHALLENGE" width="732" height="284">';
} else {
	month = '<img src="image/top_mainvisual12.jpg" alt="NEXT CHALLENGE" width="732" height="284">';
}
document.write(month);