Seat device for vehicle

A seat device for a vehicle, comprising:

• a front-row seat including a driver seat and an assistant seat;
• a rear-row seat provided behind said front-row seat, the rear-row seat comprising a seat cushion and a seat back;
• respective front-row and rear-row seats being provided in a cabin which includes an ingress and egress opening at a side face,
• wherein said rear-row seat is configured so as to be respectively located in a normal use position where the seat cushion thereof is disposed substantially horizontally and in a stored position where the seat cushion thereof is rotated upward and a longitudinal thickness thereof is made short, and said assistant seat is configured so as to be moved rearward from a position beside said driver seat to a position just in front of the rear-row seat located in the stored position,
• wherein said seat cushion of the rear-row seat is pivotally supported at a seat support member and biased by a biasing means provided at the seat support member so that the rear-row seat can take said stored position where the seat cushion thereof is rotated upward with a biasing force of said biasing means, said seat cushion of the rear-row seat is configured to be engaged with a lock member provided on a side of a vehicle floor so that the rear-row seat can take said normal use position where the seat cushion thereof is in a substantially horizontal position against the biasing force of said means, and there is provided a releasing mechanism that releases an engagement of the seat cushion of the rear-row seat with said lock member when said assistant seat is moved rearward to a specified position,
• whereby said assistant seat can be allowed to be moved rearward to said position just in front of the rear-row seat located in the stored position when the rear-row seat is changed from the normal use position to the stored position according to a release operation of the engagement of the seat cushion of the rear-row seat by said releasing mechanism.