日治時代租期的安排相當符合效率的原則，也就是說租期的安排考慮了投資的意願、當時的農耕技術型態以及交易成本。普通作物佃耕地的頭期租約在1930年代初期以前以1年為多，但是1930年代初期以後通常是3至5年。這是因為1930年代初期以前，農業技術要求較多短期便能回收利益之變動投入，尤其是勞動，也要求耗資巨大的水利設施；不過，灌溉設施之租賃制度使一般農田可以極低的成本，取得灌溉用水。因此，在這種耕作技術以及生產因素供給的特殊制度之下，普通作物1年的租期就已經足夠回收所有的投資了。 我們也發現1930年代初期以後，耕作技術變得集約化之後，租期也延長了。這是因為1930年代蓬萊米的引進，使得稻作需要投入較多的肥料與灌溉用水，也就是說耕種技術變得較以前集約了，為了提高佃農租佃土地與對土地進行投資的意願，租期需要延長之故。1920年代末期以後出現的業佃改善會在租期的延長上扮演了重要的功能，加速了這種轉變的趨勢。此外，我們也發現日治時代的租約以1年或是3至5年為限指的是頭期租約。事實上，頭期租約期滿後，若任何一方沒有違背契約的內容，通常租約得以延期。以續約的方式，有些租約維持相當長久的年代。為何不一開始就訂立一個相當長的租期，而要以續約的方式延長租期呢？這是為了降低交易成本的考慮，因為訂立長期租約需要訂立書面租約，而書面租約的關係人較多，責任較重之故，尤其是書面租約需要保證人，而保證人因為責任很重，因此很難找。綜合以上的分析，我們發現日治時代租期的訂定主要考慮的因素是屬於效率層面的。

In arranging the duration of land tenure contracts during the Japanese colonial period, the main consideration is efficiency. At the turn of 1930, the duration for most of the first contracts for the rented land of the common corps changed from 1 to 3-5 years. Before the start of the 1930s, agricultural technology rendered all sorts of variable inputs. Although installing irrigation facilities to the common crops land required big investments, the renting system enabled a lot of farmers to use low cost irrigated water, thus allowing them to reap fruits of their labor in a relatively short period of time. We also find that the introduction of the new rice strain called pon-lai-mi in the 1930s called for more intensive fertilization, which led to the extension of the duration of contracts. Decade earlier, because of the transaction costs, Taiwanese landlords were reluctant to sign long-term contracts with their tenants. But in order to provide incentives to their tenants and to encourage them to invest in new technology, landlords by the 1930s generally agreed to extend the duration of contracts. In addition, we also find that if neither party broke the contracts, most of the contracts were renewed and the extension sustained and honored. In this way, some contracts lasted for quite a long time. Based upon the above analysis, we conclude that the rule of efficiency were the deciding factors of the duration of land tenure contracts.