Provided are an endoscopic surgical device and a guide device that can satisfy the function of interlocking two medical instruments with each other. An overtube, which is punctured into a body wall and guides an endoscope and a treatment tool into a body cavity, includes an interlocking member that interlocks the forward and backward movements of the endoscope and the treatment tool with each other. The interlocking member is constituted of a first sleeve coupled to the endoscope, a second sleeve coupled to the treatment tool, and a corded flexible coupling member that couples the first sleeve and the second sleeve together. Accordingly, when the coupling member is in a relaxed state, the endoscope and the treatment tool independently move forward and backward, and when the coupling member is in a tensioned state, the endoscope and the treatment tool move forward and backward in an interlocking manner.