To provide a two-way constant pressure expansion valve which accurately keeps a constant pressure of a refrigerant in comparison with a conventional one.

As pressure sensitive portions 20A, 20B on one end side and the other end side are fixed to a body 10B in this two-way constant pressure expansion valve 10, the pressure sensitive portions 20A, 20B on one end side and the other end side themselves are not moved according to the flowing direction of the refrigerant. Accordingly, a linear motion supporting mechanism which support bellows to be retractable while controlling buckling of the bellows found in the conventional one, becomes unnecessary. Thus the constant pressure of the refrigerant is accurately kept in comparison with the conventional one without affected by sliding resistance of the linear motion supporting mechanism.

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