To provide a wheelchair with a locking device with which a user can easily fix the wheelchair to a vehicle securely and fixedly by himself without any help.

This device is designed to fix the wheelchair with a seat section positioned between right and left big wheels mounted on a frame to the floor of the vehicle. The device is provided with a striker type lock mechanism fixed on the floor, and a striker member fixed in a front part or a rear part of the frame of the wheelchair which engages with the lock mechanism when the wheelchair moves into the vehicle, and an auxiliary lock mechanism which fixes the front part or the rear part of the wheelchair linked with a riding movement on the wheelchair and releases fixation linked with the leaving movement from the wheelchair at a fixing position of wheelchair where a striker member locks with the lock mechanism, and a lock releasing mechanism for releasing the lock mechanism provided at the wheelchair fixing position.