A valve device configured to be fitted to a gas tank in which high-pressure gas is stored, the valve device comprising: a body in which a gas flow passage is provided, the gas flow passage providing communication between an inside and an outside of the gas tank; and a check valve provided in the gas flow passage, the check valve including a poppet that suppresses discharge of the gas inside the gas tank to an outside of the body, and a valve seat with which the poppet makes contact and from which the poppet separates, wherein: the poppet including a block portion is in a form of a hollow shaft, the block portion being located at a distal end of the poppet and having a taper shape, and the poppet has at least one side hole that provides communication between an inside and an outside of a portion of the poppet, the portion being in the form of the hollow shaft; and the at least one side hole extends obliquely with respect to a central axis line of the poppet such that the at least one side hole extends inclined along a gas flow direction with respect to a direction in which the poppet moves when the check valve opens, the valve device further comprising: a joint for connecting a pipe to the gas flow passage; and a positioning member having a communication hole that communicates with the gas flow passage, wherein: an outer surface of the body has a fitting hole that leads to the gas flow passage, characterized in that in the fitting hole, the joint and the positioning member are arranged in a stated order from an outer side of the body; and the positioning member is configured such that the positioning member is able to set a position of the valve seat even in a state where the joint is not fitted to the fitting hole. a body in which a gas flow passage is provided, the gas flow passage providing communication between an inside and an outside of the gas tank; and a check valve provided in the gas flow passage, the check valve including a poppet that suppresses discharge of the gas inside the gas tank to an outside of the body, and a valve seat with which the poppet makes contact and from which the poppet separates, wherein: the poppet including a block portion is in a form of a hollow shaft, the block portion being located at a distal end of the poppet and having a taper shape, and the poppet has at least one side hole that provides communication between an inside and an outside of a portion of the poppet, the portion being in the form of the hollow shaft; and the at least one side hole extends obliquely with respect to a central axis line of the poppet such that the at least one side hole extends inclined along a gas flow direction with respect to a direction in which the poppet moves when the check valve opens, the valve device further comprising: a joint for connecting a pipe to the gas flow passage; and a positioning member having a communication hole that communicates with the gas flow passage, wherein: an outer surface of the body has a fitting hole that leads to the gas flow passage, characterized in that in the fitting hole, the joint and the positioning member are arranged in a stated order from an outer side of the body; and the positioning member is configured such that the positioning member is able to set a position of the valve seat even in a state where the joint is not fitted to the fitting hole. the poppet including a block portion is in a form of a hollow shaft, the block portion being located at a distal end of the poppet and having a taper shape, and the poppet has at least one side hole that provides communication between an inside and an outside of a portion of the poppet, the portion being in the form of the hollow shaft; and the at least one side hole extends obliquely with respect to a central axis line of the poppet such that the at least one side hole extends inclined along a gas flow direction with respect to a direction in which the poppet moves when the check valve opens, the valve device further comprising: a joint for connecting a pipe to the gas flow passage; and a positioning member having a communication hole that communicates with the gas flow passage, wherein: an outer surface of the body has a fitting hole that leads to the gas flow passage, characterized in that in the fitting hole, the joint and the positioning member are arranged in a stated order from an outer side of the body; and the positioning member is configured such that the positioning member is able to set a position of the valve seat even in a state where the joint is not fitted to the fitting hole. a joint for connecting a pipe to the gas flow passage; and a positioning member having a communication hole that communicates with the gas flow passage, wherein: an outer surface of the body has a fitting hole that leads to the gas flow passage, characterized in that in the fitting hole, the joint and the positioning member are arranged in a stated order from an outer side of the body; and the positioning member is configured such that the positioning member is able to set a position of the valve seat even in a state where the joint is not fitted to the fitting hole. an outer surface of the body has a fitting hole that leads to the gas flow passage, characterized in that in the fitting hole, the joint and the positioning member are arranged in a stated order from an outer side of the body; and the positioning member is configured such that the positioning member is able to set a position of the valve seat even in a state where the joint is not fitted to the fitting hole.