A guide apparatus comprising: a first member (1, 41); a second member (2, 2a, 2b, 42, 42a, 42b) assembled to the first member (1, 41) in such a manner as to be relatively movable in a length direction; an engagement body (21, 43) placed on the second member (2, 2a, 2b, 42, 42a, 42b); and a pair of plate spring portions (22a, 22b, 44a, 44b) placed on the first member (1, 41) in such a manner as to sandwich the engagement body (21, 43), wherein the pair of plate spring portions (22a, 22b, 44a, 44b) bends in such a manner that a minimum dimension (w) between the pair of plate spring portions (22a, 22b, 44a, 44b) is smaller than a dimension (d) of the engagement body (21, 43), and in a state where the engagement body (21, 43) has gone beyond a minimum dimension position between the pair of plate spring portions (22a, 22b, 44a, 44b) and the second member (2, 2a, 2b, 42, 42a, 42b) is being held at a predetermined position on the first member (1, 41), the minimum dimension (w) between the pair of plate spring portions (22a, 22b, 44a, 44b) is smaller than the dimension (d) of the engagement body (21, 43), and both end portions, in the length direction, of each plate spring portion (22a, 22b, 44a, 44b) are supported by the first member (1, 41), one end portions (23, 44a1, 44b1), in the length direction, of the pair of plate spring portions (22a, 22b, 44a, 44b) are fixed to the first member (1, 41), the other end portions (24, 44a3, 44b3), in the length direction, of the pair of plate spring portions (22a, 22b, 44a, 44b) are supported by support surfaces (25, 41a, 41b) of the first member (1, 41) in such a manner as to be movable in the length direction, and characterised in that the other end portions (24, 44a3, 44b3), in the length direction, of the pair of plate spring portions (22a, 22b, 44a, 44b) bend, in convex form, toward the support surfaces (25, 41a, 41b). a first member (1, 41); a second member (2, 2a, 2b, 42, 42a, 42b) assembled to the first member (1, 41) in such a manner as to be relatively movable in a length direction; an engagement body (21, 43) placed on the second member (2, 2a, 2b, 42, 42a, 42b); and a pair of plate spring portions (22a, 22b, 44a, 44b) placed on the first member (1, 41) in such a manner as to sandwich the engagement body (21, 43), wherein the pair of plate spring portions (22a, 22b, 44a, 44b) bends in such a manner that a minimum dimension (w) between the pair of plate spring portions (22a, 22b, 44a, 44b) is smaller than a dimension (d) of the engagement body (21, 43), and in a state where the engagement body (21, 43) has gone beyond a minimum dimension position between the pair of plate spring portions (22a, 22b, 44a, 44b) and the second member (2, 2a, 2b, 42, 42a, 42b) is being held at a predetermined position on the first member (1, 41), the minimum dimension (w) between the pair of plate spring portions (22a, 22b, 44a, 44b) is smaller than the dimension (d) of the engagement body (21, 43), and both end portions, in the length direction, of each plate spring portion (22a, 22b, 44a, 44b) are supported by the first member (1, 41), one end portions (23, 44a1, 44b1), in the length direction, of the pair of plate spring portions (22a, 22b, 44a, 44b) are fixed to the first member (1, 41), the other end portions (24, 44a3, 44b3), in the length direction, of the pair of plate spring portions (22a, 22b, 44a, 44b) are supported by support surfaces (25, 41a, 41b) of the first member (1, 41) in such a manner as to be movable in the length direction, and characterised in that the other end portions (24, 44a3, 44b3), in the length direction, of the pair of plate spring portions (22a, 22b, 44a, 44b) bend, in convex form, toward the support surfaces (25, 41a, 41b).