Provided is a synthetic resin stent with which it is possible to improve the resistance to pressure applied radially from the outside in a state of expanded diameter even when the fibers are thinned. A synthetic resin stent 1 provided with a stent main body part 2 and a diameter expansion mechanism 3 that connects to the stent main body part 2 and changes the stent main body part 2 from a state of contracted diameter to a state of expanded diameter together with holding the stent main body part 2 in a state of expanded diameter, wherein the diameter expansion mechanism 3 is provided with a ring-shaped member 31 attached to the distal end side of the stent main body part 2, a string-shaped member 32, one end of which is connected to the proximal end side of the stent main body part 2 and inserted through the ring-shaped member 31 and the other end side of which extends to the proximal end side of the stent main body part 2, and a locking part 33 disposed in the vicinity of the connecting portion of the string-shaped member 32 and the stent main body part 2, the locking part 22 being capable of locking the ring-shaped member 31.