A stacked type fluid heater comprising: a first low temperature layer on which a plural number of low temperature side flow passages is formed to introduce therein target medium to be heated; and a first high temperature layer adjacent to the first low temperature layer, on which a plural number of high temperature side flow passages is formed to introduce therein heating medium for heating the target medium to be heated, wherein: a temperature of the target medium to be heated introduced to the plural number of low temperature side flow passages is lower than a freezing point of the heating medium; the plural number of high temperature side flow passages comprises high temperature side flow passages adjacent to each other through a component of the first high temperature layer; the first high temperature layer is adjacent to a second high temperature layer on which a plural number of high temperature side flow passages is formed to introduce therein heating medium comprising the same fluid as said heating medium; and the plural number of high temperature side flow passages of the first high temperature layer and the plural number of high temperature side flow passages of the second high temperature layer are adjacent to each other through at least one of a component of the first high temperature layer and a component of the second high temperature layer, characterized by a high temperature side supply header that supplies heating medium to be introduced into the plural number of high temperature side flow passages of the first high temperature layer, and heating medium to be introduced into the plural number of high temperature side flow passages of the second high temperature layer. a first low temperature layer on which a plural number of low temperature side flow passages is formed to introduce therein target medium to be heated; and a first high temperature layer adjacent to the first low temperature layer, on which a plural number of high temperature side flow passages is formed to introduce therein heating medium for heating the target medium to be heated, wherein: a temperature of the target medium to be heated introduced to the plural number of low temperature side flow passages is lower than a freezing point of the heating medium; the plural number of high temperature side flow passages comprises high temperature side flow passages adjacent to each other through a component of the first high temperature layer; the first high temperature layer is adjacent to a second high temperature layer on which a plural number of high temperature side flow passages is formed to introduce therein heating medium comprising the same fluid as said heating medium; and the plural number of high temperature side flow passages of the first high temperature layer and the plural number of high temperature side flow passages of the second high temperature layer are adjacent to each other through at least one of a component of the first high temperature layer and a component of the second high temperature layer, characterized by a high temperature side supply header that supplies heating medium to be introduced into the plural number of high temperature side flow passages of the first high temperature layer, and heating medium to be introduced into the plural number of high temperature side flow passages of the second high temperature layer. a temperature of the target medium to be heated introduced to the plural number of low temperature side flow passages is lower than a freezing point of the heating medium; the plural number of high temperature side flow passages comprises high temperature side flow passages adjacent to each other through a component of the first high temperature layer; the first high temperature layer is adjacent to a second high temperature layer on which a plural number of high temperature side flow passages is formed to introduce therein heating medium comprising the same fluid as said heating medium; and the plural number of high temperature side flow passages of the first high temperature layer and the plural number of high temperature side flow passages of the second high temperature layer are adjacent to each other through at least one of a component of the first high temperature layer and a component of the second high temperature layer, characterized by a high temperature side supply header that supplies heating medium to be introduced into the plural number of high temperature side flow passages of the first high temperature layer, and heating medium to be introduced into the plural number of high temperature side flow passages of the second high temperature layer.