To solve a problem of impossibility of conducting pilot injection of favorable precision in a conventional distribution type fuel injection pump because of incapability of adjusting a valve opening pressure of an accumulation piston composing an injection ratio control mechanism after distribution type fuel injection is composed, and accumulation quantity of the injection ratio control mechanism, which are fixed to be constant.

In the injection ratio control mechanism 31 of a fuel injection pump 1, an adjusting mechanism to adjust accumulation quantity of the injection ratio control mechanism 31, that is a piston stroke St, and a valve opening pressure of the accumulation piston 32 from the outer side during operation of the distribution type fuel injection pump 1 is provided.