本文探討了臺灣石化業的主要部門塑膠原料業的成長過程以及成長的原因， 也探 究了上游石化基本原料業與下游塑膠製品業對其成長的影響。 這產業中除了 PVC 發展較早外， 其他則都是在公營企業開始經營上游的輕油裂解廠之同時 隨著設廠生產，是典型的向前連鎖效應，而推動者則為國家。 這六個產業從開始到 1986 年為止，都大致維持相當的成長率，之後則各業有顯著不同的表 現。在早期下游的需求對於各產業而言，都是主要的成長動力，同時下游帶動作用越大的產 業，其成長率就越快，顯現了一種動態的雪球效果。同時，技術變革、產業的成長潛能與市 場競爭程度之間也呈現動態的相關性，並影響著產業的成長。 政策因素對這產業有很深的影響，除了以公營企業經營上游並在啟始階段領導推動之外，政 府一直採用各種關稅與非關稅的保護措施來扶植這產業，直到 1986 年開始貿易的自由化為 止。同時這也是臺灣發展的一個典型，即出口導向政策常配合著中上游的進口替代，顯示這 兩種政策並非是相互排斥的選擇。

　　　　　This paper rexplores the history and causes of grwoth of Taiwan's plasticmaterial industry, which lies vertically between the upstream basic petrochemicals and the downstream plastic product sectors. The study focuses on the six common plstics, PVC, IDPE, HDPE, PP, PS, and ABS, which comprise over 80% of the sector. Almost all of them were established along with the state-run upstream naphtha-cracking plants. That is, forward linkage effects were effective. All grew steadily until liberalization in 1986. For those sectors, whose inputs cannot be easily transported, their growth began to be restricted since the late 1980s when local protest postponed the construction of the fifth and sixth cracker. For other sectors their growth has been unhampered. PS and ABS sectors grew rapidly by expanding their exports, especially to the mainland, in the later period. The downstream's demand has been the engine of growth for all six sectors. The backward linkage effects, however, are stronger in those sectors that did not face supply restriction and those that grew faster. The greater the downstream's grwoth rate, the better its prospects, the greater the linkage effects and the faster the midstream's growth. Market structure also matters. Moreover, industrial policy has been instrumental in bringing about industrial upgrading. That is, ladder-climbing does not come automatically for an NIC.