A seat sliding device includes a lever member, a lock member, a biasing member, and an operation member. The biasing member is formed of a bar-shaped member and includes a front acting portion configured to come in contact with a front end of the lever member to bias the front end of the lever member upward, a rear acting portion configured to come in contact with a rear end of the lever member to bias the rear end of the lever member upward, and an intermediate support portion formed between the front acting portion and the rear acting portion and engaged with a an engaging portion formed in an upper rail. The engaging portion supports the intermediate support portion at a position rearward of a turning center of the lever member (shaft member).