Kanazawa is located in about 180 miles northwest of Tokyo, facing the Sea of Japan.
From Tokyo Narita International Airport as well as Haneda Airport, ANA(All Nippon Airways) and JAL(Japan Airlines) offer direct flights to Komatsu Airport. Flight time is about 1 hour. From Komatsu Airport, you can take airport bus to central Kanazawa in about 1 hour.
Tokyo and Kanazawa are directly connected by the bullet trains named JR Hokuriku Shinkansen. It takes 2.5 to 3 hours, costs around 14,000 yen. You can find timetables here.
If you have a plan to travel around Japan by train besides Kanazawa, it may be cost effective to buy the Japan Rail Pass which is provided only for foreign tourists and offers unlimited use of JR trains in fixed price. You can find the details here.
Kanazawa is also easy to access from other major cities such as Osaka and Nagoya.